JP2019066164A - Refrigerant amount estimating method and air-conditioner - Google Patents

Abstract

To provide a refrigerant amount estimating method and an air-conditioner to which the method can be applied, which can highly accurately estimate a refrigerant amount in an air-conditioner.SOLUTION: An air-conditioner 1 includes a refrigerant circuit 10 constituted by connecting the component devices including a compressor 21, an outdoor heat exchanger 23, indoor expansion valves 41, 51, 38 (expansion mechanism), an indoor heat exchanger 42, 52. The refrigerant estimating method performed in the air-conditioner 1 includes a control step (step S11) and an estimate step (step S12). In the control step, each of the component devices are controlled to function the indoor heat exchanger 42, 52 as an evaporator, and a refrigerant amount estimating operation (step S116) is executed in which the heat is at an overheat level SHr which is higher than a normal operation. In the estimate step, the refrigerant amount M in the refrigerant circuit 10 is estimated by using a state amount of the refrigerant flowing in the refrigerant circuit 10 in the refrigerant amount estimating operation and an operation state amount of each of the component device.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a refrigerant amount estimation method and an air conditioner.

  Conventionally, methods for calculating the amount of refrigerant charged in the refrigerant circuit of an air conditioner have been considered. For example, Patent Document 1 (Japanese Patent No. 4705878) discloses an air conditioner that can determine the suitability of the amount of refrigerant in the refrigerant circuit.

  In the technology described in Patent Document 1, the amount of refrigerant in the indoor heat exchanger that functions as an evaporator is obtained based on the parameters obtained by regression analysis of the test or simulation result.

  However, since there are many variations in the indoor heat exchanger, it takes a lot of time and labor to measure the amount of refrigerant in the indoor heat exchanger for each variation. On the other hand, even if the amount of refrigerant in the indoor heat exchanger is to be calculated by a formula, since the refrigerant in the indoor heat exchanger is in a gas-liquid two-phase state, it is difficult to set appropriate experimental parameters. As a result, the amount of refrigerant in the indoor heat exchanger can not be calculated with high accuracy, and an error may be included in the calculation result of the amount of refrigerant in the entire refrigerant circuit.

  An object of the present invention is to provide a refrigerant amount estimation method capable of accurately estimating the refrigerant amount in an air conditioner and an air conditioner to which the method can be applied.

  An air conditioner according to a first aspect of the present invention has a refrigerant circuit configured by connecting respective constituent devices including a compressor, an outdoor heat exchanger, an expansion mechanism, and an indoor heat exchanger. This air conditioning apparatus controls each component to operate the indoor heat exchanger as an evaporator, and executes a refrigerant amount estimation operation with a degree of superheat higher than that in the normal operation.

  In the air conditioner according to the first aspect, the indoor heat exchanger functions as an evaporator, and the refrigerant amount estimation operation is performed so as to have a higher degree of superheat than that in the normal operation; The amount of liquid phase refrigerant can be reduced. Here, the amount of refrigerant can be estimated with high accuracy using the experimental regression equation in the case of the refrigerant present in the outdoor heat exchanger or the like rather than the refrigerant present in the indoor heat exchanger. Therefore, by distributing the refrigerant to components other than the indoor heat exchanger, it is possible to estimate the amount of refrigerant in the refrigerant circuit with high accuracy.

  A refrigerant quantity estimation method according to a second aspect of the present invention includes an air conditioner having a refrigerant circuit configured by connecting various components including a compressor, an outdoor heat exchanger, an expansion mechanism, and an indoor heat exchanger. Estimate the amount of refrigerant in the This refrigerant quantity estimation method includes a control step and an estimation step. In the control step, each component is controlled to operate the indoor heat exchanger as an evaporator, and a refrigerant amount estimation operation with a higher degree of superheat than that in the normal operation is performed. In the estimation step, the amount of refrigerant in the refrigerant circuit is estimated using the amount of state of the refrigerant flowing through the refrigerant circuit in the refrigerant amount estimation operation or the amount of operation state of each component.

  In the refrigerant quantity estimation method according to the second aspect, the indoor heat exchanger functions as an evaporator, and the refrigerant quantity estimation operation with a higher degree of superheat than that in the normal operation is performed. The amount of refrigerant can be reduced. Further, the amount of refrigerant present in the outdoor heat exchanger can be estimated with high accuracy using experimental regression, as compared with the refrigerant present in the indoor heat exchanger. Therefore, by distributing the refrigerant to components other than the indoor heat exchanger by the refrigerant amount estimating method according to the first aspect, it is possible to estimate the amount of refrigerant in the refrigerant circuit with high accuracy.

  In addition, the "normal operation" mentioned here means an operation in which the degree of superheat is, for example, about 3 to 5 degrees, and the evaporation temperature is 10 degrees or more when the indoor temperature is 20 degrees or more.

  The refrigerant quantity estimation method according to the third aspect of the present invention is the refrigerant quantity estimation operation according to the second aspect, wherein in the control step, the degree of superheat is in the range of 10 degrees to 20 degrees in the refrigerant quantity estimation operation. Make it

  In the refrigerant quantity estimation method according to the second aspect, the degree of superheat is in the range of 10 degrees or more and 20 degrees or less in the refrigerant quantity estimation operation. Thus, it is possible to estimate the amount of refrigerant in the refrigerant circuit with high accuracy while maintaining the reliability. Supplementally, by setting the degree of superheat to 10 degrees or more, the dry area in the indoor heat exchanger functioning as an evaporator can be increased, and the amount of refrigerant can be reduced. As a result, it is possible to reduce the calculation error when calculating the amount of refrigerant in the entire refrigerant circuit. On the other hand, if the degree of superheat exceeds 20 degrees, the compressor discharge temperature may exceed the reliability temperature upper limit. Therefore, the reliability can be maintained by setting the degree of superheat to 20 degrees or less.

  A refrigerant quantity estimation method according to a fourth aspect of the present invention is the refrigerant quantity estimation method according to the second aspect or the third aspect, wherein, in the control step, the air conditioning apparatus is lower than normal operation in the refrigerant quantity estimation operation. Operate at evaporation temperature.

  In the refrigerant quantity estimation method according to the fourth aspect, the indoor heat exchanger functions as an evaporator, and the refrigerant quantity estimation operation is performed so that the evaporation temperature is lower than that in the normal operation. Can reduce the amount of refrigerant in the liquid phase. Therefore, it is possible to reduce the calculation error when calculating the refrigerant amount of the entire refrigerant circuit.

  A refrigerant quantity estimation method according to a fifth aspect of the present invention is the refrigerant quantity estimation method according to the fourth aspect, wherein, in the control step, the evaporation temperature is 0 degrees Celsius or more and 10 degrees Celsius or less in the refrigerant quantity estimation operation. Within the range.

  In the refrigerant amount estimation method according to the fifth aspect, by setting the evaporation temperature to 0 ° C. or more, frost can be prevented from being generated in the indoor heat exchanger functioning as an evaporator. Further, by setting the evaporation temperature to 10 ° C. or less, the refrigerant amount estimation operation can be performed under substantially any indoor temperature condition.

  A refrigerant quantity estimation method according to a sixth aspect of the present invention is the refrigerant quantity estimation method according to the second aspect to the fifth aspect, wherein the refrigerant in the air conditioner has a compressor whose operating capacity can be varied by changing the rotational speed. It is an estimate of the quantity. Then, in the control step, in the refrigerant amount estimation operation, the rotation number of the compressor is changed so that the circulating amount of the refrigerant becomes constant.

  In the refrigerant quantity estimation method according to the sixth aspect, in the refrigerant quantity estimation operation, the number of rotations of the compressor is changed so that the circulation quantity of the refrigerant becomes constant, so the flow in each heat exchanger Since the same results are obtained under the conditions, the repeatability and repeatability can be enhanced. That is, the amount of refrigerant in the outdoor heat exchanger can be calculated using a highly accurate experimental regression equation. As a result, the amount of refrigerant in the refrigerant circuit can be estimated with high accuracy.

  The refrigerant quantity estimation method according to a seventh aspect of the present invention is the refrigerant quantity estimation method according to the sixth aspect, wherein each component device is controlled in the control step to set the circulation quantity of the refrigerant in the refrigerant circuit at rated operation. The refrigerant amount estimation operation is performed so as to be lower than that.

  In the refrigerant quantity estimation method according to the seventh aspect, the refrigerant quantity estimation operation is performed with the circulation quantity of the refrigerant in the refrigerant circuit being lower than that during rated operation, so the refrigerant flow in each heat exchanger is stabilized. Can be As a result, the reproducibility and repeatability can be enhanced, and the amount of refrigerant in the refrigerant circuit can be estimated with high accuracy.

  In addition, when the circulation amount of a refrigerant | coolant is too low, a high pressure refrigerant | coolant may become inadequate and the situation which an air-conditioning capacity is not fully exhibited may arise. Therefore, when performing the refrigerant amount estimation operation, the minimum value of the circulation amount is set to such an extent that the air conditioning capacity can be sufficiently exhibited.

  The refrigerant quantity estimation method according to an eighth aspect of the present invention is the refrigerant quantity estimation method according to the seventh aspect, wherein at the control step, each constituent device is controlled to set the circulation quantity of the refrigerant in the refrigerant circuit at rated operation. The refrigerant amount estimation operation is performed so as to be 40% or less.

  In the refrigerant amount estimating method according to the eighth aspect, the refrigerant amount estimating operation is performed such that the circulating amount of the refrigerant in the refrigerant circuit is 40% or less than that in the normal operation. As a result, it is possible to make the circulating amount of the refrigerant lower than in the normal operation while maintaining a state in which the heating and cooling capacity is sufficiently exhibited. As a result, the amount of refrigerant in the refrigerant circuit can be estimated with high accuracy.

  A refrigerant quantity estimation method according to a ninth aspect of the present invention is the refrigerant quantity estimation method according to the second aspect to the eighth aspect, wherein liquid refrigerant from the outdoor heat exchanger to the indoor heat exchanger during refrigerant quantity estimation operation An air conditioner further comprising: a connecting pipe through which the air flows, a temperature control device controlling the temperature of the connecting pipe, an outdoor fan changing the temperature of the outdoor heat exchanger, and an indoor fan changing the temperature of the indoor heat exchanger Estimate the amount of refrigerant in the Here, in the refrigerant amount estimation operation, the evaporation temperature in the refrigerant circuit, the condensation temperature, the degree of supercooling corresponding to the difference between the temperature of the liquid refrigerant in the connection pipe and the condensation temperature, the degree of superheat, and the circulating amount of the refrigerant are the indoor temperature and the outdoor A target value corresponding to the temperature is set. Then, in the control step, when all of the evaporation temperature, the condensation temperature, the degree of supercooling, the degree of superheat, and the circulating amount of the refrigerant reach a predetermined range from the target value, the number of rotations of the compressor, the temperature The values of the control output of the control device, the opening degree of the expansion mechanism, the rotation speed of the outdoor fan, and the rotation speed of the indoor fan are fixed.

  In the refrigerant quantity estimation method according to the ninth aspect, the refrigerant flow can be stabilized in the refrigerant quantity estimation operation. As a result, the amount of refrigerant in the refrigerant circuit can be estimated with high accuracy.

  A refrigerant quantity estimation method according to a tenth aspect of the present invention is the refrigerant quantity estimation method according to the second aspect to the ninth aspect, wherein liquid refrigerant from the outdoor heat exchanger to the indoor heat exchanger during refrigerant quantity estimation operation The first connection piping through which the refrigerant flows, the second connection piping through which the gas refrigerant flows from the indoor heat exchanger to the outdoor heat exchanger during refrigerant quantity estimation operation, and the first connection piping downstream of the outdoor heat exchanger The amount of refrigerant in the air conditioning apparatus further includes a branch pipe branched and connected to the second connection pipe. Then, in the control step, the refrigerant in the branch pipe is adjusted in flow rate by the flow valve and depressurized, and the refrigerant not flowing into the branch pipe from the first connection pipe and the refrigerant flowing into the branch pipe through the heat exchanger Heat is exchanged, and the refrigerant flowing into the branch pipe is merged with the refrigerant in the second connection pipe.

  In the refrigerant quantity estimation method according to the tenth aspect, a branch pipe is provided between the first connection pipe and the second connection pipe that connect the outdoor heat exchanger and the indoor heat exchanger, and the liquid refrigerant in the first connection pipe is By exchanging heat of the gas refrigerant in the branch piping, liquid temperature control of the liquid refrigerant in the first connection piping is realized. Thereby, the refrigerant weight in the liquid pipe can be made the same state in any operation state by making the liquid refrigerant in the first connection pipe into the supercooling state in the same temperature state, and thereby the outdoor unit and the indoor unit Since the total amount of refrigerant in the unit can be maintained as well, the reproducibility and repeatability can be enhanced under any operating conditions. As a result, the amount of refrigerant can be detected with high accuracy.

  An air conditioner according to an eleventh aspect includes a refrigerant circuit configured by connecting each component including a compressor, an outdoor heat exchanger, an expansion mechanism, and at least one indoor heat exchanger. . This air conditioner makes the indoor heat exchanger function as an evaporator, makes the rotational speed of the compressor low regardless of the indoor load, and the degree of superheat of the suctioned vapor in the compressor is higher than that in the normal operation A control unit is provided to control each component device so as to stabilize for a predetermined time. Such a configuration makes it possible to estimate the amount of refrigerant in the refrigerant circuit with high accuracy.

  The term "expansion mechanism" as used herein refers to a mechanism capable of depressurizing the refrigerant, and, for example, an expansion valve corresponds to this.

  An air conditioner according to a twelfth aspect is the air conditioner according to the eleventh aspect, including a plurality of indoor units each having an indoor heat exchanger. And a control part controls each component so that the degree of superheat of all the indoor units under operation may be stabilized in a state higher than usual operation. Such a configuration makes it possible to estimate the amount of refrigerant in the refrigerant circuit with high accuracy in an air conditioning apparatus having a plurality of indoor units.

  The air conditioning apparatus according to a thirteenth aspect is the air conditioning apparatus according to the eleventh aspect or the twelfth aspect, and the control unit controls each component device such that the degree of superheat becomes 5 degrees or more.

  An air conditioner according to a fourteenth aspect is the air conditioner according to the eleventh aspect, comprising: an outdoor unit having an outdoor heat exchanger; and an indoor unit having an indoor heat exchanger; One outdoor unit corresponds to the outdoor unit. Further, the control unit controls each component device so that the degree of superheat is 8 degrees or more. With such a configuration, in the air conditioning apparatus in which one indoor unit corresponds to one outdoor unit, it is possible to estimate the amount of refrigerant in the refrigerant circuit with high accuracy.

  An air conditioning apparatus according to a fifteenth aspect is the air conditioning apparatus according to any of the eleventh aspect through the fourteenth aspect, wherein the control unit is configured to maintain a state of superheat higher than in normal operation for 5 minutes or more. Control each component. Thereby, the estimation accuracy of the amount of refrigerant can be enhanced.

  An air conditioner according to a sixteenth aspect is the air conditioner according to any of the eleventh through fifteenth aspects, wherein the control unit uses the state quantity of the refrigerant flowing through the refrigerant circuit or the operating state quantity of each component The amount of refrigerant in the refrigerant circuit is calculated.

  An air conditioner according to a seventeenth aspect is the air conditioner according to the sixteenth aspect, wherein when the control unit calculates the amount of refrigerant in the refrigerant circuit, the degree of superheat is in the range of 10 degrees to 20 degrees. Be inside.

  A control method according to an eighteenth aspect relates to an air conditioner having a refrigerant circuit configured by connecting respective constituent devices including a compressor, an outdoor heat exchanger, an expansion mechanism, and at least one indoor heat exchanger. It is a control method for calculating the amount of refrigerant. In this control method, the indoor heat exchanger functions as an evaporator, the rotational speed of the compressor is reduced regardless of the indoor load, and the degree of heating of suction vapor in the compressor is higher than in normal operation. Control each component to be stable in time. Thus, the refrigerant can be distributed to components other than the indoor heat exchanger.

  A control method according to a nineteenth aspect is the control method according to the eighteenth aspect, and is used for an air conditioner having a plurality of indoor units individually having indoor heat exchangers. In this control method, each component is controlled so that the degree of superheat of all the indoor units in operation is stabilized in a state higher than normal operation.

  A control method according to a twentieth aspect is the control method according to the eighteenth aspect or the nineteenth aspect, and controls each component device such that the degree of superheat becomes 5 degrees or more.

  A control method according to a twenty first aspect is the control method according to the eighteenth aspect, including an outdoor unit having an outdoor heat exchanger and an indoor unit having an indoor heat exchanger, wherein one outdoor unit One indoor unit is used for the corresponding air conditioner. In this control method, each component is controlled so that the degree of superheat is 8 degrees or more.

  A control method according to a twenty second aspect is the control method according to any of the eighteenth aspect through the twenty first aspect, wherein each component device is controlled such that a state in which the degree of superheat is higher than that during normal operation lasts for 5 minutes or more. .

  The refrigerant quantity estimating method according to the twenty-third aspect executes one of the control methods according to the eighteenth and twenty-second aspects, and then uses the state quantity of the refrigerant flowing through the refrigerant circuit or the operating state quantity of each component device. Calculate the amount of refrigerant in the refrigerant circuit. This makes it possible to estimate the amount of refrigerant in the refrigerant circuit with high accuracy.

  The refrigerant quantity estimation method according to a twenty-fourth aspect is the refrigerant quantity estimation method according to the twenty-third aspect, wherein when calculating the quantity of refrigerant in the refrigerant circuit, the degree of superheat is in the range of 10 degrees to 20 degrees. Do.

  In the air conditioner according to the first aspect, it is possible to estimate the amount of refrigerant in the refrigerant circuit with high accuracy.

  In the refrigerant quantity estimation method according to the second aspect, the refrigerant quantity in the refrigerant circuit can be estimated with high accuracy.

  In the refrigerant quantity estimation method according to the third aspect, the refrigerant quantity in the refrigerant circuit can be estimated with high accuracy while maintaining the reliability.

  In the refrigerant quantity estimation method according to the fourth aspect, it is possible to reduce the calculation error when calculating the refrigerant quantity of the entire refrigerant circuit.

  In the refrigerant quantity estimation method according to the fifth aspect, frost can be prevented from being generated in the indoor heat exchanger functioning as an evaporator.

  In the refrigerant quantity estimation method according to the sixth aspect, the refrigerant quantity of the outdoor heat exchanger can be calculated using a highly accurate experimental regression equation.

  In the refrigerant amount estimation method according to the seventh aspect, reproducibility and repeatability can be enhanced.

  In the refrigerant quantity estimation method according to the eighth aspect, it is possible to make the circulating quantity of the refrigerant lower than in the normal operation while maintaining a state in which the heating and cooling capacity is sufficiently exhibited.

  In the refrigerant quantity estimation method according to the ninth aspect, the refrigerant flow can be stabilized in the refrigerant quantity estimation operation.

  In the refrigerant quantity estimation method according to the tenth aspect, the evaporation temperature lower than that in the normal operation can be easily achieved.

  The air conditioning apparatus according to the eleventh to seventeenth aspects can estimate the amount of refrigerant in the refrigerant circuit with high accuracy.

  The control method according to the eighteenth to twenty-second aspects can distribute the refrigerant to constituent devices other than the indoor heat exchanger.

  The refrigerant quantity estimation method according to the twenty-third and twenty-fourth aspects can estimate the refrigerant quantity in the refrigerant circuit with high accuracy.

It is a schematic block diagram of the air conditioning apparatus 1 which concerns on one Embodiment of this invention. It is a control block diagram of the air conditioning apparatus concerning the embodiment. It is a flowchart for demonstrating "the trial run mode (refrigerant automatic filling operation)" concerning the embodiment. It is a flowchart for demonstrating the refrigerant | coolant amount estimation driving | operation which concerns on the same embodiment. It is a schematic diagram (illustration of a four-way switching valve etc. is abbreviate | omitted) which shows the state of the refrigerant | coolant which flows through the inside of the refrigerant circuit in refrigerant | coolant amount estimation driving | operation which concerns on the embodiment. It is a flowchart for demonstrating the estimation method of the refrigerant | coolant amount which concerns on the embodiment. It is a flowchart for demonstrating "the refrigerant | coolant leak detection driving | operation mode" which concerns on the embodiment. It is a figure which shows the relationship between the refrigerant | coolant amount in an evaporator, and evaporation temperature. It is a schematic block diagram of the air conditioning apparatus 1 which concerns on the modification B. FIG. It is a schematic block diagram of the air conditioning apparatus 1 which concerns on the modification D. FIG.

  An embodiment of an air conditioner according to the present invention will be described below based on the drawings.

(1) Configuration of Air Conditioning Apparatus FIG. 1 is a schematic configuration diagram of an air conditioning apparatus 1 according to an embodiment of the present invention. The air conditioning apparatus 1 is an apparatus used for cooling and heating a room such as a building by performing a vapor compression refrigeration cycle operation. The air conditioning apparatus 1 mainly includes an outdoor unit 2 as one heat source unit, indoor units 4 and 5 as utilization units (two in the present embodiment) connected in parallel to the outdoor unit 2, and the outdoor A liquid refrigerant communication pipe 6 and a gas refrigerant communication pipe 7 as refrigerant communication pipes that connect the unit 2 and the indoor units 4 and 5 are provided. That is, the vapor compression type refrigerant circuit 10 of the air conditioner 1 of the present embodiment is connected by the outdoor unit 2, the indoor units 4 and 5, the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 7. It is configured.

(1-1) Indoor Unit The indoor units 4 and 5 are installed by being embedded or suspended in a ceiling of a room such as a building or by hanging on a wall of the room. The indoor units 4 and 5 are connected to the outdoor unit 2 via the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 7, and constitute a part of the refrigerant circuit 10.

  Next, the configuration of the indoor units 4 and 5 will be described. In addition, since the indoor unit 4 and the indoor unit 5 have the same configuration, only the configuration of the indoor unit 4 will be described here, and the configuration of the indoor unit 5 will be the 40th unit showing each part of the indoor unit 4. Instead of the reference numerals, the reference numerals in the 50s are attached, and the explanation of each part is omitted.

  The indoor unit 4 mainly includes an indoor-side refrigerant circuit 10a (in the indoor unit 5, an indoor-side refrigerant circuit 10b) which constitutes a part of the refrigerant circuit 10. The indoor refrigerant circuit 10a mainly includes an indoor expansion valve 41 as an expansion mechanism and an indoor heat exchanger 42 as a use side heat exchanger.

  In the present embodiment, the indoor expansion valve 41 is an electric expansion valve connected to the liquid side of the indoor heat exchanger 42 in order to adjust the flow rate of the refrigerant flowing in the indoor refrigerant circuit 10a.

  In the present embodiment, the indoor heat exchanger 42 is a cross fin type fin-and-tube heat exchanger composed of a heat transfer pipe and a large number of fins, and functions as a refrigerant evaporator during cooling operation. It is a heat exchanger that cools indoor air and functions as a refrigerant condenser during heating operation to heat indoor air.

  In the present embodiment, after the indoor unit 4 sucks indoor air into the unit and exchanges heat with the refrigerant in the indoor heat exchanger 42, the indoor fan 43 as a blower fan for supplying the air indoors as the supply air. have. The indoor fan 43 is a fan capable of changing the air volume Wr of the air supplied to the indoor heat exchanger 42, and in the present embodiment, a centrifugal fan or a multi-blade fan driven by a motor 43a comprising a DC fan motor. Etc.

  The indoor unit 4 is also provided with various sensors. A liquid side temperature sensor 44 is provided on the liquid side of the indoor heat exchanger 42 to detect the temperature of the refrigerant (that is, the refrigerant temperature corresponding to the condensation temperature Tc in the heating operation or the evaporation temperature Te in the cooling operation) There is. On the gas side of the indoor heat exchanger 42, a gas side temperature sensor 45 that detects the temperature Teo of the refrigerant is provided. An indoor temperature sensor 46 for detecting the temperature of indoor air flowing into the unit (that is, the indoor temperature Tr) is provided on the indoor air suction port side of the indoor unit 4. In the present embodiment, the liquid side temperature sensor 44, the gas side temperature sensor 45 and the indoor temperature sensor 46 are composed of thermistors. Further, the indoor unit 4 has an indoor side control unit 47 that controls the operation of each part constituting the indoor unit 4. And the indoor side control part 47 has a microcomputer, a memory, etc. provided for controlling the indoor unit 4, and is a remote controller (not shown) for individually operating the indoor units 4. It is possible to exchange control signals etc. between them and exchange control signals etc. with the outdoor unit 2 through the transmission line 8a.

(1-2) Outdoor Unit The outdoor unit 2 is installed outside the building or the like, and is connected to the indoor units 4 and 5 via the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 7. , 5 constitute the refrigerant circuit 10.

  Next, the configuration of the outdoor unit 2 will be described. The outdoor unit 2 mainly includes an outdoor side refrigerant circuit 10 c which constitutes a part of the refrigerant circuit 10. The outdoor refrigerant circuit 10 c mainly includes a compressor 21, a four-way switching valve 22, an outdoor heat exchanger 23 as a heat source side heat exchanger, an outdoor expansion valve 38 as an expansion mechanism, and an accumulator 24. A subcooler 25 as a temperature control mechanism, a liquid side shut-off valve 26 and a gas side shut-off valve 27 are provided.

  The compressor 21 is a compressor whose operating capacity can be varied, and in the present embodiment, a positive displacement compressor driven by a motor 21 a whose rotation speed Rm is controlled by an inverter. In the present embodiment, only one compressor 21 is used. However, the present invention is not limited to this. Two or more compressors may be connected in parallel according to the number of connected indoor units and the like.

  The four-way switching valve 22 is a valve for switching the flow direction of the refrigerant, and during the cooling operation, the outdoor heat exchanger 23 serves as a condenser of the refrigerant compressed by the compressor 21 and the indoor heat exchanger 42. , 52 to connect the discharge side of the compressor 21 and the gas side of the outdoor heat exchanger 23 in order to function as an evaporator of the refrigerant condensed in the outdoor heat exchanger 23, and the suction side of the compressor 21 (specific Specifically, the accumulator 24) is connected to the side of the gas refrigerant communication pipe 7 (see the solid line of the four-way switching valve 22 in FIG. 1), and the compressors 21 compress the indoor heat exchangers 42 and 52 during heating operation. In order to cause the outdoor heat exchanger 23 to function as an evaporator for the refrigerant condensed in the indoor heat exchangers 42 and 52 as a condenser for the refrigerant to be used, the discharge side of the compressor 21 and the gas refrigerant communication pipe 7 side Connect with It is possible to connect the gas side of the suction side and the outdoor heat exchanger 23 of Rutotomoni compressor 21 (see dashed four-way switching valve 22 in FIG. 1).

  In the present embodiment, the outdoor heat exchanger 23 is a cross fin type fin-and-tube heat exchanger composed of a heat transfer pipe and a large number of fins, and functions as a refrigerant condenser during cooling operation, It is a heat exchanger that functions as a refrigerant evaporator during heating operation. The gas side of the outdoor heat exchanger 23 is connected to the four-way switching valve 22, and the liquid side is connected to the liquid refrigerant communication pipe 6.

  In the present embodiment, the outdoor expansion valve 38 is an electric expansion valve connected to the liquid side of the outdoor heat exchanger 23 in order to adjust the pressure, flow rate, and the like of the refrigerant flowing in the outdoor refrigerant circuit 10c.

  In the present embodiment, the outdoor unit 2 has an outdoor fan 28 as a blower fan for discharging outdoor air after sucking outdoor air into the unit and exchanging heat with a refrigerant in the outdoor heat exchanger 23. ing. The outdoor fan 28 is a fan capable of changing the air volume Wo of the air supplied to the outdoor heat exchanger 23. In the present embodiment, the outdoor fan 28 is a propeller fan or the like driven by a motor 28a including a DC fan motor. .

  The accumulator 24 is connected between the four-way switching valve 22 and the compressor 21 and can store surplus refrigerant generated in the refrigerant circuit 10 in accordance with fluctuations in the operating load of the indoor units 4 and 5, etc. Container.

  The subcooler 25 is a double-pipe heat exchanger in the present embodiment, and is provided to cool the refrigerant sent to the indoor expansion valves 41 and 51 after being condensed in the outdoor heat exchanger 23. ing. The subcooler 25 is connected between the outdoor expansion valve 38 and the liquid side shut-off valve 26 in the present embodiment.

  In the present embodiment, a bypass refrigerant circuit 61 as a cooling source of the subcooler 25 is provided. In the following description, the portion excluding the bypass refrigerant circuit 61 from the refrigerant circuit 10 will be referred to as a main refrigerant circuit for convenience.

  The bypass refrigerant circuit 61 is connected to the main refrigerant circuit so that part of the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51 is branched from the main refrigerant circuit and returned to the suction side of the compressor 21. There is. Specifically, the bypass refrigerant circuit 61 branches a part of the refrigerant sent from the outdoor expansion valve 38 to the indoor expansion valves 41 and 51 from the position between the outdoor heat exchanger 23 and the subcooler 25. It has a branch circuit 61a connected and a junction circuit 61b connected to the suction side of the compressor 21 so as to return the suction side of the compressor 21 from the outlet on the bypass refrigerant circuit side of the subcooler 25. The branch circuit 61 a is provided with a bypass expansion valve 62 for adjusting the flow rate of the refrigerant flowing through the bypass refrigerant circuit 61. Here, the bypass expansion valve 62 is an electric expansion valve. Thus, the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51 is cooled by the refrigerant flowing through the bypass refrigerant circuit 61 after being decompressed by the bypass expansion valve 62 in the subcooler 25. That is, the capacity control of the subcooler 25 is performed by adjusting the opening degree of the bypass expansion valve 62.

  The liquid side shut-off valve 26 and the gas side shut-off valve 27 are valves provided at connection ports with external devices and pipes (specifically, the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 7). The liquid side shutoff valve 26 is connected to the outdoor heat exchanger 23. The gas-side shutoff valve 27 is connected to the four-way switching valve 22.

  In addition, the outdoor unit 2 is provided with various sensors. Specifically, the outdoor unit 2 includes a suction pressure sensor 29 that detects a suction pressure Ps of the compressor 21, a discharge pressure sensor 30 that detects a discharge pressure Pd of the compressor 21, and a suction temperature Ts of the compressor 21. And a discharge temperature sensor 32 that detects the discharge temperature Td of the compressor 21. The suction temperature sensor 31 is provided at a position between the accumulator 24 and the compressor 21. In the outdoor heat exchanger 23, a heat exchange temperature sensor for detecting the temperature of the refrigerant flowing in the outdoor heat exchanger 23 (that is, the refrigerant temperature corresponding to the condensation temperature Tc in the cooling operation or the evaporation temperature Te in the heating operation) 33 are provided. A liquid side temperature sensor 34 for detecting the temperature Tco of the refrigerant is provided on the liquid side of the outdoor heat exchanger 23. At the outlet of the subcooler 25 on the side of the main refrigerant circuit, a liquid pipe temperature sensor 35 for detecting the temperature of the refrigerant (that is, the liquid pipe temperature Tlp) is provided. The merging circuit 61 b of the bypass refrigerant circuit 61 is provided with a bypass temperature sensor 63 for detecting the temperature of the refrigerant flowing through the outlet of the subcooler 25 on the bypass refrigerant circuit side. An outdoor temperature sensor 36 that detects the temperature of outdoor air flowing into the unit (that is, the outdoor temperature Ta) is provided on the outdoor air suction port side of the outdoor unit 2. In the present embodiment, the suction temperature sensor 31, the discharge temperature sensor 32, the heat exchange temperature sensor 33, the liquid side temperature sensor 34, the liquid pipe temperature sensor 35, the outdoor temperature sensor 36 and the bypass temperature sensor 63 are thermistors. In addition, the outdoor unit 2 includes an outdoor control unit 37 that controls the operation of each part that constitutes the outdoor unit 2. The outdoor side control unit 37 has a microcomputer provided to control the outdoor unit 2, a memory, an inverter circuit for controlling the motor 21a, and the like, and the indoor side control unit of the indoor units 4 and 5 It is possible to exchange control signals etc. between 47 and 57 via the transmission line 8a. That is, the control unit 8 configured to control the operation of the entire air conditioning apparatus 1 is configured by the indoor side control units 47 and 57, the outdoor control unit 37, and the transmission lines 8a connecting the control units 37, 47 and 57. There is.

  The control unit 8 is connected to be able to receive detection signals of the various sensors 29 to 36, 44 to 46, 54 to 56, 63, as shown in FIG. The various devices 21, 24, 28a, 43a and the valves 22, 38, 41, 51, 53a, 62 are connected so as to be able to be controlled. Further, the control unit 8 is connected to a warning display unit 9 formed of an LED or the like for notifying that the refrigerant leakage has been detected in the refrigerant leakage detection operation described later. Here, FIG. 2 is a control block diagram of the air conditioner 1.

(1-3) Refrigerant communication piping The liquid refrigerant communication piping 6 and the gas refrigerant communication piping 7 are refrigerant piping to be constructed on site when the air conditioner 1 is installed in a building or other installation location, and the installation location Depending on the installation conditions such as the combination of the outdoor unit and the indoor unit, those having various lengths and tube diameters are used.

  As described above, the refrigerant circuits 10 of the air conditioner 1 are configured by connecting the indoor refrigerant circuits 10a and 10b, the outdoor refrigerant circuit 10c, the liquid refrigerant communication pipe 6, and the gas refrigerant communication pipe 7. ing. Further, the refrigerant circuit 10 can be rephrased to be composed of the bypass refrigerant circuit 61 and the main refrigerant circuit excluding the bypass refrigerant circuit 61.

(1-4) Control Unit The air conditioner 1 of the present embodiment has a cooling operation and heating by the four-way switching valve 22 by the control unit 8 configured by the indoor side control units 47 and 57 and the outdoor control unit 37. The operation is switched and the operation is performed, and control of each device of the outdoor unit 2 and the indoor units 4 and 5 is performed according to the operation load of the indoor units 4 and 5. In other words, the operation control of the air conditioner 1 is performed by the control unit 8 (more specifically, the transmission line 8a connecting the indoor control units 47 and 57, the outdoor control unit 37, and the control units 37 and 47, 57 Done by).

  In addition, the control unit 8 has an arithmetic function, and executes arithmetic processing for estimating the amount of refrigerant described later.

(2) Operation of Air Conditioning Device Next, the operation of the air conditioning device 1 of the present embodiment will be described.

  The operation modes of the air conditioner 1 of the present embodiment mainly include a normal operation mode, a test operation mode, and a refrigerant leakage detection operation mode.

  In the “normal operation mode”, control of components constituting the outdoor unit 2 and the indoor units 4 and 5 is executed in accordance with the operation load of the indoor units 4 and 5. The normal operation includes a cooling operation for cooling the room and a heating operation for heating the room.

  In the “test operation mode”, control for performing a test operation performed after the installation of the components of the air conditioner 1 is performed. The trial operation is not limited to after the initial installation of the device, and may be performed, for example, after remodeling such as adding or removing a component such as an indoor unit or after repairing a failure of the device. Further, at the time of trial operation, “automatic refrigerant charging operation” for charging the refrigerant in the refrigerant circuit 10 is performed.

  In the “refrigerant leak detection operation mode”, control for determining the presence or absence of the refrigerant leakage from the refrigerant circuit 10 is executed after the trial operation is ended and the normal operation is started.

  Hereinafter, the operation in each operation mode of the air conditioner 1 will be described in detail.

(2-1) Normal Operation Mode (2-1-1) Cooling Operation First, the cooling operation in the normal operation mode will be described with reference to FIGS. 1 and 2.

  In the cooling operation, the indoor heat exchangers 42 and 52 function as evaporators to lower the temperature of the indoor air.

  Specifically, during the cooling operation, the four-way switching valve 22 is in the state shown by the solid line in FIG. 1, that is, the discharge side of the compressor 21 is connected to the gas side of the outdoor heat exchanger 23, and the suction of the compressor 21 is The side is connected to the gas side of the indoor heat exchangers 42, 52 via the gas side shut-off valve 27 and the gas refrigerant communication pipe 7. The outdoor expansion valve 38 is fully opened. Further, the liquid side shutoff valve 26 and the gas side shutoff valve 27 are opened. Each indoor expansion valve 41, 51 is such that the degree of superheat SHr of the refrigerant at the outlet of the indoor heat exchangers 42, 52 (that is, the gas side of the indoor heat exchangers 42, 52) becomes constant at the target superheat degree SHrs. The opening degree is adjusted. Further, the opening degree of the bypass expansion valve 62 is adjusted so that the degree of superheat SHb of the refrigerant at the outlet on the side of the bypass refrigerant circuit of the subcooler 25 becomes the target degree of superheat value SHbs.

  Then, when the compressor 21, the outdoor fan 28 and the indoor fans 43, 53 are activated in such a state of the refrigerant circuit 10, the low pressure gas refrigerant is drawn into the compressor 21 and compressed to be a high pressure gas refrigerant. . The high-pressure gas refrigerant is sent to the outdoor heat exchanger 23 via the four-way switching valve 22, exchanges heat with the outdoor air supplied by the outdoor fan 28, condenses, and becomes a high-pressure liquid refrigerant. The high pressure liquid refrigerant passes through the outdoor expansion valve 38 and flows into the subcooler 25. At this time, part of the refrigerant that has passed through the outdoor expansion valve 38 is branched to the bypass refrigerant circuit 61. Then, the refrigerant flowing into the subcooler 25 and the refrigerant branched into the bypass refrigerant circuit 61 exchange heat. As a result, the refrigerant flowing into the subcooler 25 is subcooled. The supercooled high pressure liquid refrigerant is sent to the indoor units 4 and 5 via the liquid side shut-off valve 26 and the liquid refrigerant communication pipe 6. The high pressure liquid refrigerant sent to the indoor units 4 and 5 is decompressed to near the suction pressure Ps of the compressor 21 by the indoor expansion valves 41 and 51, and becomes a low pressure gas-liquid two-phase refrigerant to perform indoor heat exchange. Are sent to the vessels 42, 52. The refrigerant in the gas-liquid two-phase state exchanges heat with the indoor air in the indoor heat exchangers 42 and 52 and evaporates to become a low-pressure gas refrigerant. At this time, the temperature of the air in the room decreases. Then, the low pressure gas refrigerant is sent to the outdoor unit 2 via the gas refrigerant communication pipe 7, and flows into the accumulator 24 via the gas side shut-off valve 27 and the four-way switching valve 22. The low-pressure gas refrigerant that has flowed into the accumulator 24 is again sucked into the compressor 21.

  The refrigerant branched into the bypass refrigerant circuit 61 is reduced in pressure by the bypass expansion valve 62 and then returned to the suction side of the compressor 21. Here, a part of the refrigerant passing through the bypass expansion valve 62 is evaporated by being reduced to the vicinity of the suction pressure Ps of the compressor 21. Then, the refrigerant flowing from the outlet of the bypass expansion valve 62 of the bypass refrigerant circuit 61 toward the suction side of the compressor 21 passes through the subcooler 25 and the outdoor heat exchanger 23 on the main refrigerant circuit side to the indoor unit 4. , And heat exchange with the high-pressure liquid refrigerant sent to 5.

  The degree of superheat SHr of the refrigerant at the outlet of each indoor heat exchanger 42, 52 described above is the refrigerant detected by the liquid side temperature sensors 44, 54 from the refrigerant temperature value detected by the gas side temperature sensors 45, 55. The suction pressure Ps of the compressor 21 detected by subtracting a temperature value (corresponding to the evaporation temperature Te) or detected by the suction pressure sensor 29 is converted to a saturation temperature value corresponding to the evaporation temperature Te It is detected by subtracting the saturation temperature value of the refrigerant from the refrigerant temperature value detected by the side temperature sensors 45, 55. Further, although not adopted in the present embodiment, a temperature sensor for detecting the temperature of the refrigerant flowing in each indoor heat exchanger 42, 52 is provided, and the refrigerant temperature corresponding to the evaporation temperature Te detected by this temperature sensor The degree of superheat SHr of the refrigerant at the outlet of each indoor heat exchanger 42, 52 may be detected by subtracting the value from the refrigerant temperature value detected by the gas side temperature sensors 45, 55.

  Further, the superheat degree SHb of the refrigerant at the outlet on the bypass refrigerant circuit side of the subcooler 25 described above sets the suction pressure Ps of the compressor 21 detected by the suction pressure sensor 29 to a saturation temperature value corresponding to the evaporation temperature Te. It is detected by subtracting the saturation temperature value of the refrigerant from the refrigerant temperature value detected by the bypass temperature sensor 63 after conversion. Further, although not adopted in the present embodiment, a temperature sensor is provided at the inlet of the bypass refrigerant circuit side of the subcooler 25, and the refrigerant temperature value detected by this temperature sensor is detected by the bypass temperature sensor 63 The degree of superheat SHb of the refrigerant at the outlet of the bypass refrigerant circuit side of the subcooler 25 may be detected by subtraction from the temperature value.

(2-1-2) Heating Operation Next, the heating operation in the normal operation mode will be described using FIGS. 1 and 2.

  In the heating operation, the indoor heat exchangers 42 and 52 function as a condenser to raise the temperature of the indoor air.

  Specifically, at the time of heating operation, the four-way switching valve 22 is shown by the broken line in FIG. 1, that is, the discharge side of the compressor 21 is the indoor heat exchanger 42 via the gas side shutoff valve 27 and the gas refrigerant communication pipe 7. , 52, and the suction side of the compressor 21 is connected to the gas side of the outdoor heat exchanger 23. The outdoor expansion valve 38 is adjusted in opening degree in order to reduce the pressure flowing into the outdoor heat exchanger 23 to a pressure at which the outdoor heat exchanger 23 can evaporate (that is, the evaporation pressure Pe). Further, the liquid side shutoff valve 26 and the gas side shutoff valve 27 are in an open state. The degree of opening of the indoor expansion valves 41, 51 is adjusted so that the degree of subcooling SCr of the refrigerant at the outlets of the indoor heat exchangers 42, 52 becomes constant at the degree of supercooling target value SCrs.

  Then, when the compressor 21, the outdoor fan 28 and the indoor fans 43, 53 are activated in the state of the refrigerant circuit 10 as described above, the low pressure gas refrigerant is drawn into the compressor 21 and compressed to be a high pressure gas refrigerant. Become. The high-pressure gas refrigerant is sent to the indoor units 4 and 5 via the four-way switching valve 22, the gas side closing valve 27 and the gas refrigerant connection pipe 7. The high-pressure gas refrigerant sent to the indoor units 4 and 5 exchanges heat with indoor air in the indoor heat exchangers 42 and 52 and condenses to be a high-pressure liquid refrigerant. At this time, the temperature of the air in the room rises. When the high-pressure liquid refrigerant passes through the indoor expansion valves 41, 51, the pressure is reduced according to the opening degree of the indoor expansion valves 41, 51. The refrigerant that has passed through the indoor expansion valves 41 and 51 is sent to the outdoor unit 2 via the liquid refrigerant communication pipe 6, and is further depressurized via the liquid side shut-off valve 26, the subcooler 25 and the outdoor expansion valve 38. After that, it becomes a low-pressure gas-liquid two-phase refrigerant and flows into the outdoor heat exchanger 23. The low-pressure gas-liquid two-phase refrigerant that has flowed into the outdoor heat exchanger 23 exchanges heat with the outdoor air supplied by the outdoor fan 28 and evaporates to become a low-pressure gas refrigerant. Flow into the accumulator 24. The low-pressure gas refrigerant that has flowed into the accumulator 24 is again sucked into the compressor 21.

  The degree of subcooling SCr of the refrigerant at the outlets of the indoor heat exchangers 42 and 52 described above converts the discharge pressure Pd of the compressor 21 detected by the discharge pressure sensor 30 into a saturation temperature value corresponding to the condensation temperature Tc It is detected by subtracting the refrigerant temperature value detected by the liquid side temperature sensors 44 and 54 from the saturation temperature value of the refrigerant. Further, although not adopted in the present embodiment, a temperature sensor is provided for detecting the temperature of the refrigerant flowing in each indoor heat exchanger 42, 52, and the refrigerant temperature corresponding to the condensation temperature Tc detected by this temperature sensor The degree of subcooling SCr of the refrigerant at the outlet of the indoor heat exchangers 42, 52 may be detected by subtracting the value from the refrigerant temperature value detected by the liquid side temperature sensors 44, 54. Further, the bypass expansion valve 62 is closed.

(2-2) Trial Operation Mode FIG. 3 is a flowchart for explaining the trial operation mode.

  In the trial operation, for example, the outdoor unit 2 filled with refrigerant in advance and the indoor units 4 and 5 are installed at an installation place such as a building, and connected via the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 7 It is performed after the circuit 10 is configured. In the trial operation, first, the liquid side shutoff valve 26 and the gas side shutoff valve 27 of the outdoor unit 2 are opened, and the refrigerant circuit 10 is filled with the refrigerant previously filled in the outdoor unit 2. Next, the operator issues a command to start trial operation to the control unit 8 directly or remotely via a remote control (not shown) or the like. In response to this, the control unit 8 executes the processing of steps S11 to S13 shown in FIG. The process of each step will be described in detail below.

(2-2-1) Step S11: Refrigerant amount estimation operation (2-2-1-1) Indoor unit 100% operation In trial operation, it is determined whether the amount of refrigerant is insufficient or not, and it is determined that the amount is insufficient. The refrigerant amount automatic charging operation is performed. Therefore, first, “refrigerant amount estimation operation” is performed to determine whether the refrigerant is insufficient. FIG. 4 is a flowchart for explaining the refrigerant amount estimation operation.

  When the start command of the refrigerant amount estimation operation is issued (S111), the compressor 21, the outdoor fan 28, and the indoor fans 43 and 53 are activated, and the cooling operation is forcibly performed for all the indoor units 4 and 5 (hereinafter, The indoor unit 100% operation is performed (S112). Specifically, the refrigerant circuit 10 is in a state where the four-way switching valve 22 of the outdoor unit 2 is shown by the solid line in FIG. 1, and the indoor expansion valves 41, 51 and the outdoor expansion valve 38 of the indoor units 4 and 5 are Each component is controlled to be in the open state.

  As a result, the refrigerant in the refrigerant circuit 10 is in the state as shown in FIG. 5 (illustration of the four-way switching valve 22 etc. is omitted). That is, in the refrigerant circuit 10, the high-pressure gas refrigerant compressed and discharged in the compressor 21 flows in the flow path from the compressor 21 to the outdoor heat exchanger 23 functioning as a condenser (hatched line in FIG. Portions from the compressor 21 to the outdoor heat exchanger 23 in the hatched portion). In addition, a high pressure refrigerant whose phase changes from a gas state to a liquid state flows in the outdoor heat exchanger 23 functioning as a condenser due to heat exchange with outdoor air (hatched portions in FIG. 5 and hatched portions in black) See the part corresponding to the outdoor heat exchanger 23). In addition, high-pressure liquid refrigerant flows through the flow path from the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51 and the flow path from the outdoor heat exchanger 23 to the bypass expansion valve 62 (shown in FIG. See the hatched part of). Further, in the portions of the indoor heat exchangers 42 and 52 functioning as an evaporator and the portion on the bypass refrigerant circuit side of the subcooler 25, heat exchange with indoor air causes a phase from a gas-liquid two-phase state to a gas state Varying low pressure refrigerant flows (portions of the indoor heat exchangers 42 and 52 and portions of the subcooler 25 in the grid hatching and hatching hatching in FIG. 5). Further, a flow path from the indoor heat exchangers 42, 52 to the compressor 21 (a flow path including the gas refrigerant communication pipe 7 and the accumulator 24) and a portion from the bypass refrigerant circuit side of the subcooler 25 to the compressor 21. A low pressure gas refrigerant flows in the flow path (a portion from the indoor heat exchangers 42 and 52 to the compressor 21 in the hatched portion in FIG. 5 and a portion on the bypass refrigerant circuit side of the subcooler 25 To the compressor 21).

  Subsequently, the control unit 8 controls the following steps S113 to S116 to stabilize the state of the refrigerant circulating in the refrigerant circuit 10. The following steps S113 to S116 may be performed in random order.

(2-2-1-2) Step S113: Refrigerant Circulation Amount Control The control unit 8 controls the operating capacity of the compressor 21 so that the refrigerant circulation amount Wc flowing in the refrigerant circuit 10 becomes constant (hereinafter referred to as “refrigerant” It is referred to as "circulation amount control" (S113). The refrigerant circulation amount control is performed in the outdoor heat exchanger 23 in order to prevent the refrigerant amount and the degree of subcooling from fluctuating non-linearly due to the change of the refrigerant circulation amount Wc. Supplementally, the high-pressure refrigerant changes its phase from a gas state to a liquid state according to the amount of heat exchange with outdoor air (a portion corresponding to the outdoor heat exchanger among hatched portions of hatched and hatched in FIG. In the process of changing the amount of refrigerant inside the condenser by referring to the condenser unit A), the amount of refrigerant and the degree of subcooling may change non-linearly due to the change in the amount Wc of circulating refrigerant. In order to prevent this, the refrigerant circulation amount Wc flowing in the refrigerant circuit 10 is made constant.

  In the refrigerant circulation amount control, the operating capacity of the compressor 21 is controlled by the motor 21a whose rotation speed Rm is controlled by the inverter. Then, by making the refrigerant circulation amount Wc constant, the distribution state of the gas refrigerant and the liquid refrigerant in the condenser section A is stabilized. As a result, it is possible to bring about a change in the degree of subcooling of the outlet of the condenser section A due to the change in the amount of refrigerant in the condenser section A.

  The refrigerant circulation amount Wc is calculated based on the amount of state of the refrigerant flowing in the refrigerant circuit 10 or the amount of operating state of the component. The rotational speed of the motor 21a of the compressor 21 is controlled such that the calculated refrigerant circulation amount Wc becomes the circulation amount target value Wcs. Here, if the circulation amount target value Wcs is set large, there is a possibility that the operable outside air condition and the room temperature condition may be limited to a narrow range. Therefore, it is desirable to set the circulation amount target value Wcs to be as low as possible. In the present embodiment, the circulation amount target value Wcs is set to 40% or less of the refrigerant circulation amount when the compressor 21 is operated at the rated rotation speed. Further, the refrigerant circulation amount Wc is expressed as a function of the evaporation temperature Te and the condensation temperature Tc (that is, Wc = f (Te, Tc)).

  The operating state quantities used to calculate the refrigerant circulation amount Wc are not limited to this, and the evaporation temperature Te, the condensation temperature Tc, the suction temperature Ts which is the refrigerant temperature on the suction side of the compressor 21, The suction pressure Ps which is the refrigerant pressure at the suction side, the discharge temperature Td which is the refrigerant temperature at the discharge side of the compressor 21, the discharge pressure Pd which is the refrigerant pressure at the discharge side of the compressor 21, the outdoor heat exchanger 23 as a condenser Calculation is performed using at least one of the compressor discharge superheat degree SHm, which is the superheat degree of the refrigerant at the inlet side of the inlet, and the supercooling degree SCo of the refrigerant at the outlet side of the outdoor heat exchanger 23 as a condenser. It is possible.

  By performing such refrigerant circulation amount control, the heat exchange performance in the outdoor heat exchanger 23 is stabilized, and the state of the refrigerant in the condenser portion A is stabilized.

(2-2-1-3) Step S114: Condensation Pressure Control Further, the controller 8 controls the outdoor fan 28 to perform an outdoor operation so that the condensation pressure Pc of the refrigerant in the outdoor heat exchanger 23 functioning as a condenser becomes constant. The air volume Wo of the outdoor air supplied to the heat exchanger 23 is controlled (hereinafter referred to as "condensing pressure control") (S114). Condensation pressure control is performed to stabilize the state of the refrigerant flowing in the condenser section A. Supplementally, since the amount of refrigerant in the above-mentioned condenser part A is greatly affected by the condensing pressure Pc of the refrigerant, condensation pressure control is performed when estimating the amount of refrigerant.

  Specifically, the condensation pressure Pc of the refrigerant in the condenser portion A described above changes more than the influence of the outdoor temperature Ta. Therefore, the influence of the outdoor temperature Ta is excluded by controlling the air volume Wo of the outdoor air supplied from the outdoor fan 28 to the outdoor heat exchanger 23 by the motor 28a. Thus, the state of the refrigerant flowing in the condenser section A can be stabilized.

  Note that the control of the condensation pressure Pc by the outdoor fan 28 of the present embodiment is performed by the discharge pressure Pd of the compressor 21 detected by the discharge pressure sensor 30 or the inside of the outdoor heat exchanger 23 detected by the heat exchange temperature sensor 33. The temperature of the refrigerant flowing through (i.e., the condensation temperature Tc) is used. The discharge pressure Pd or the condensation temperature Tc is an operating state amount equivalent to the condensation pressure Pc of the refrigerant in the outdoor heat exchanger 23.

  By performing such condensation pressure control, the flow path from the outdoor heat exchanger 23 to the indoor expansion valves 41, 51 (the outdoor expansion valve 38, the portion on the main refrigerant circuit side of the subcooler 25 and the liquid refrigerant communication pipe 6 Flow path including the flow path and the flow path from the outdoor heat exchanger 23 to the bypass expansion valve 62 of the bypass refrigerant circuit 61 (refer to the hatched portion in FIG. A high pressure liquid refrigerant flows in B). Then, the liquid refrigerant flow portion B is sealed by the liquid refrigerant and is in a stable state.

(2-2-1-4) Step S115: Liquid pipe temperature control Further, the control unit 8 controls the subcooler 25 so that the temperature of the refrigerant sent from the subcooler 25 to the indoor expansion valves 41 and 51 becomes constant. Control the capacity of the unit (hereinafter referred to as "liquid tube temperature control") (S115). The liquid pipe temperature control is performed in the refrigerant pipe including the liquid refrigerant communication pipe 6 extending from the subcooler 25 to the indoor expansion valves 41 and 51 (from the subcooler 25 to the indoor expansion valve in the liquid refrigerant circulating portion B shown in FIG. This is done in order not to change the density of the refrigerant (41, 51). The capacity control of the subcooler 25 is realized by adjusting the amount of heat exchange between the refrigerant flowing on the main refrigerant circuit side of the subcooler 25 and the refrigerant flowing on the bypass refrigerant circuit side. Specifically, the temperature Tlp of the refrigerant detected by the liquid pipe temperature sensor 35 provided at the outlet on the main refrigerant circuit side of the subcooler 25 by changing the flow rate of the refrigerant flowing through the bypass refrigerant circuit 61 is the liquid pipe The temperature target value Tlps is made constant. The flow rate of the refrigerant flowing through the bypass refrigerant circuit 61 is increased or decreased by adjusting the opening degree of the bypass expansion valve 62.

  By performing such liquid pipe temperature control, the influence of the change in the temperature Tco of the refrigerant at the outlet of the outdoor heat exchanger 23 can be contained only in the refrigerant pipe extending from the outlet of the outdoor heat exchanger 23 to the supercooler 25. Can. For example, as the amount of refrigerant in refrigerant circuit 10 gradually increases by filling refrigerant circuit 10 with refrigerant, the temperature Tco of the refrigerant at the outlet of outdoor heat exchanger 23 (ie, the temperature of outdoor heat exchanger 23 The degree of subcooling SCo of the refrigerant at the outlet may change. Even in such a case, the influence of the change in the temperature Tco of the refrigerant at the outlet of the outdoor heat exchanger 23 can be obtained by performing the liquid pipe temperature control, the refrigerant from the subcooler 25 to the indoor expansion valves 41 and 51 It can be made not to affect piping (liquid refrigerant communication piping 6 etc.).

(2-2-1-5) Step S116: Superheat Control Further, the control unit 8 controls the indoor expansion valves 41, 51 so that the superheat SHr of the indoor heat exchangers 42, 52 functioning as an evaporator becomes constant. Are controlled (hereinafter referred to as "superheat control") (S116). The degree of superheat control is performed to stabilize the state of the refrigerant flowing in the evaporator section C. Supplementally, since the amount of refrigerant in the evaporator section C is greatly affected by the dryness of the refrigerant at the outlets of the indoor heat exchangers 42, 52, the degree of superheat control is performed when estimating the amount of refrigerant.

  Specifically, by controlling the opening degree of the indoor expansion valves 41, 51, the gas side of the indoor heat exchangers 42, 52 (hereinafter, in the description regarding the refrigerant amount estimation operation, the outlet of the indoor heat exchangers 42, 52) ) So that the degree of superheat SHr of the refrigerant in the above becomes constant at the target degree of superheat SHrs (ie, the gas refrigerant at the outlet of the indoor heat exchangers 42, 52 is put into Stabilize the state of the flowing refrigerant. As a result, a state in which the gas refrigerant reliably flows in the gas refrigerant flow part D is created.

  Further, at the time of superheat degree control, the control unit 8 makes the superheat degree SHr to be higher than that in the normal operation. Specifically, the degree of superheat SHr is in the range of 10 degrees to 20 degrees. The degree of superheat in normal operation is about 3 to 5 degrees. In order to increase the degree of superheat SHr, the control unit 8 controls the evaporation temperature Te to be lower than the normal temperature. For example, the control unit 8 sets the evaporation temperature Te lower than that in the normal operation such that the evaporation temperature Te is in the range of 0 ° C. or more and 10 ° C. or less in the room temperature range of 20 ° C. or more and 30 ° C. or less. Control to be Further, the control unit 8 makes the air volume Wr of the indoor air supplied to the indoor heat exchangers 42, 52 by the indoor fans 43, 53 constant in order to stabilize the evaporation pressure Pe of the refrigerant.

(2-2-1-6)
By each control as described above, the state of the refrigerant circulating in the refrigerant circuit 10 is stabilized, and the distribution of the amount of refrigerant in the refrigerant circuit 10 becomes constant. Therefore, when the refrigerant circuit 10 is additionally charged with the refrigerant, it is possible to create a state in which a change in the amount of refrigerant in the refrigerant circuit 10 appears as a change in the amount of refrigerant in the outdoor heat exchanger 23.

  Note that, unlike the present embodiment, when the outdoor unit 2 is not filled with the refrigerant in advance, the refrigerant has an amount of refrigerant that does not cause an abnormal stop of the component prior to the process of step S11. Do the filling.

(2-2-2) Step S12: Calculation of Refrigerant Amount In the test operation, the refrigerant circuit 10 is additionally filled with the refrigerant while performing the above-described refrigerant amount estimation operation. At this time, the control unit 8 functions as a refrigerant amount estimation unit that estimates the refrigerant amount. The control unit 8 calculates and estimates the amount of refrigerant in the refrigerant circuit 10 from the amount of state of the refrigerant flowing through the refrigerant circuit 10 or the amount of operating state of the component when the refrigerant is additionally charged. As described later, the refrigerant circuit 10 is divided into a plurality of portions, and the control unit 8 calculates the amount of refrigerant for each of the divided portions.

  In step S12, the refrigerant circuit 10 is in a state where the four-way switching valve 22 is indicated by a solid line in FIG. That is, the discharge side of the compressor 21 is connected to the gas side of the outdoor heat exchanger 23. Further, the suction side of the compressor 21 is connected to the outlets of the indoor heat exchangers 42, 52 via the gas side shut-off valve 27 and the gas refrigerant communication pipe 7.

  In this state, the refrigerant circuit 10 includes the high pressure gas pipe portion E, the condenser portion A, the high temperature side liquid pipe portion B1, the low temperature side liquid pipe portion B2, the liquid refrigerant communication piping portion B3, and the indoor unit portion F , A gas refrigerant communication pipe G, a low pressure gas pipe H, and a bypass circuit I.

  The “high pressure gas pipe portion E” is a portion from the compressor 21 and the portion from the compressor 21 to the outdoor heat exchanger 23 including the four-way switching valve 22 (not shown in FIG. 5).

  “Condenser unit A” is a portion of the outdoor heat exchanger 23.

  The “high-temperature side liquid pipe portion B1” is an inlet side half of a portion from the outdoor heat exchanger 23 to the subcooler 25 and a portion on the main refrigerant circuit side of the subcooler 25 in the liquid refrigerant circulating portion B.

  “Low temperature side liquid pipe portion B2” is a liquid side shut-off valve 26 (not shown in FIG. 5) from the outlet side half of the portion of liquid refrigerant flow portion B on the main refrigerant circuit side of subcooler 25 and Part).

  The “liquid refrigerant communication piping portion B3” is a portion of the liquid refrigerant communication portion B that is the liquid refrigerant communication piping 6.

  The “indoor unit F” includes gas refrigerant flowing from the liquid refrigerant communication pipe B to the indoor expansion valves 41 and 51 and the indoor heat exchangers 42 and 52 (that is, the evaporator C) from the liquid refrigerant communication pipe 6 Part D is a portion up to the gas refrigerant communication pipe 7.

  The “gas refrigerant communication piping portion G” is a portion of the gas refrigerant communication portion D of the gas refrigerant communication piping 7.

  The “low pressure gas pipe portion H” is a portion of the gas refrigerant flow portion D from the gas side shut-off valve 27 (not shown in FIG. 5) to the compressor 21 including the four-way switching valve 22 and the accumulator 24.

  The “bypass circuit portion I” is a portion from the high temperature side liquid pipe portion B1 of the liquid refrigerant circulating portion B to the low pressure gas pipe portion H including the bypass expansion circuit 62 and the bypass cooler circuit side portion of the subcooler 25. .

  And the control part 8 which functions as a refrigerant | coolant amount estimation part calculates the refrigerant | coolant amount for every divided | segmented part, as shown to the flowchart of FIG. The following steps S121 to S129 may be performed in random order.

(2-2-2-1) Step S121: High-pressure gas pipe section E
The control unit 8 calculates the refrigerant amount Mog1 in the high pressure gas pipe portion E based on the following equation 1 (S121).
[Equation 1]
Mog1 = Vog1 × ρd

  That is, the refrigerant amount Mog1 is expressed as a functional expression in which the volume Vog1 of the high pressure gas pipe portion E of the outdoor unit 2 is multiplied by the density dd of the refrigerant in the high pressure gas pipe portion E. The volume Vog1 of the high-pressure gas pipe section E is a known value before the outdoor unit 2 is installed at the installation location, and is stored in advance in the memory of the control unit 8. Further, the density dd of the refrigerant in the high pressure gas pipe portion E is obtained by converting the discharge temperature Td and the discharge pressure Pd.

(2-2-2-2) Step S122: Condenser unit A
Further, the control unit 8 calculates the refrigerant amount Mc in the condenser unit A based on the following equation 2 (S122).
[Equation 2]
Mc = kc1 × Ta + kc2 × Tc + kc3 × SHm
+ Kc5 × ρc + kc6 × ρco + kc7

  That is, the refrigerant amount Mc is a function expression of the outdoor temperature Ta, the condensation temperature Tc, the compressor discharge superheat degree SHm, the saturated liquid density ρc of the refrigerant in the outdoor heat exchanger 23, and the density coco of the refrigerant at the outlet of the outdoor heat exchanger 23. It is represented as The parameters kc1 to kc7 are obtained by regression analysis of the results of the test and the detailed simulation, and are stored in advance in the memory of the control unit 8. Further, the compressor discharge superheat degree SHm is a superheat degree of the refrigerant on the discharge side of the compressor 21. The compressor discharge superheat degree SHm is obtained by converting the discharge pressure Pd into the saturation temperature value of the refrigerant and subtracting the saturation temperature value of the refrigerant from the discharge temperature Td. The saturated liquid density ρc of the refrigerant is obtained by converting the condensation temperature Tc. The density ρco of the refrigerant at the outlet of the outdoor heat exchanger 23 is obtained by converting the condensing pressure Pc obtained by converting the condensing temperature Tc and the temperature Tco of the refrigerant.

(2-2-2-3) Step S123: High-temperature side liquid pipe portion B1
Further, the control unit 8 calculates the refrigerant amount Mol1 in the high temperature side liquid pipe portion B1 based on the following formula 3 (S123).
[Equation 3]
Mol1 = Vol1 × ρco

  That is, the refrigerant amount Mol1 is the density ρco of the refrigerant in the high temperature side liquid pipe portion B1 (ie, the density of the refrigerant at the outlet of the outdoor heat exchanger 23 described above) in the volume Vol1 of the high temperature side liquid pipe portion B1 of the outdoor unit 2S. It is expressed as a multiplied function equation. The volume Vol1 of the high temperature side liquid pipe portion B1 is a known value before the outdoor unit 2 is installed at the installation location, and is stored in advance in the memory of the control unit 8.

(2-2-2-4) Step S124: Low temperature side liquid pipe portion B2
In addition, the control unit 8 calculates the refrigerant amount Mol2 in the low temperature side liquid pipe portion B2 based on the following formula 4 (S124).
[Equation 4]
Mol2 = Vol2 × ρlp

  That is, the refrigerant amount Mol2 is expressed as a functional expression in which the volume Vol2 of the low temperature side liquid pipe portion B2 of the outdoor unit 2 is multiplied by the density lplp of the refrigerant in the low temperature side liquid pipe portion B2. The volume Vol2 of the low temperature side liquid pipe portion B2 is a known value before the outdoor unit 2 is installed at the installation location, and is stored in advance in the memory of the control unit 8. Further, the density lplp of the refrigerant in the low temperature side liquid pipe portion B2 is the density of the refrigerant at the outlet of the subcooler 25, and is obtained by converting the condensing pressure Pc and the temperature Tlp of the refrigerant at the outlet of the subcooler 25. .

(2-2-2-5) Step S125: Liquid refrigerant communication piping portion B3
Further, the control unit 8 calculates the amount of refrigerant Mlp in the liquid refrigerant communication piping unit B3 based on the following equation 5 (S125).
[Equation 5]
Mlp = Vlp × ρlp

  That is, the refrigerant amount Mlp is expressed as a functional expression in which the volume Vlp of the liquid refrigerant communication pipe 6 is multiplied by the density lplp of the refrigerant in the liquid refrigerant communication pipe portion B3 (that is, the density of the refrigerant at the outlet of the subcooler 25). . The liquid refrigerant communication pipe 6 is constructed on site when the air conditioning apparatus 1 is installed in a place such as a building. Therefore, the volume Vlp of the liquid refrigerant communication pipe 6 is calculated by the control unit 8 based on the information obtained at the site such as the length and the pipe diameter.

［数７］

［数８］

［数９］

［数１０］

(2-2-2-6) Step S126: Indoor unit F
Further, the control unit 8 calculates the amount of refrigerant Mr in the indoor unit portion F (S126). In the indoor unit portion F, the refrigerant is in a gas-liquid two-phase flow state. Therefore, the control unit 8 executes simulation calculation of the refrigeration cycle characteristics according to the structure of the indoor unit portion F. Specifically, the control unit 8 calculates the refrigerant amount Mr by solving a simultaneous equation of a continuous equation (the following equation 6), an equation of motion (the following equation 7), and an energy equation (the following equation 8). Further, when the calculation is carried out, the void ratio α (the following formula 9) and the Smith formula (the following formula 10) are used. In Smith's equation, e is a virtual average liquid ratio, and C is a correction term of gas-liquid velocity ratio, and these are experimental parameters. Further, x means quality, ρL means liquid density, and ρG means gas density. In addition, 0.4 is a recommendation value of a virtual average liquid ratio. Here, although two indoor units 4 and 5 are present, the total refrigerant amount of the indoor unit portion F is calculated by adding the respective refrigerant amounts.
[Equation 6]

[Equation 7]

[Equation 8]

[Equation 9]

[Equation 10]

(2-2-2-7) Step S127: Gas refrigerant communication piping G
Further, the control unit 8 calculates the amount of refrigerant Mgp in the gas refrigerant communication piping G based on the following equation 11 (S127).
[Equation 11]
Mgp = Vgp × ρgp

  That is, the refrigerant amount Mgp is expressed as a functional expression in which the volume Vgp of the gas refrigerant communication pipe 7 is multiplied by the density gpgp of the refrigerant in the gas refrigerant communication pipe portion G. In the same manner as the liquid refrigerant communication pipe 6, the gas refrigerant communication pipe 7 is constructed on site when the gas refrigerant communication pipe 7 installs the air conditioning apparatus 1 at an installation place such as a building. Therefore, the volume Vgp of the gas refrigerant communication pipe 7 is calculated by the control unit 8 based on the information obtained at the site such as the length and the pipe diameter. Further, the density gpgp of the refrigerant in the gas refrigerant communication pipe G is the density ss of the refrigerant on the suction side of the compressor 21 and the refrigerant at the outlet of the indoor heat exchangers 42 and 52 (ie, the inlet of the gas refrigerant communication pipe 7) The average value of the density ρeo of The density ss of the refrigerant on the suction side of the compressor 21 is obtained by converting the suction pressure Ps and the suction temperature Ts. Further, the density eoeo of the refrigerant at the outlet of the indoor heat exchangers 42, 52 is obtained by converting the evaporation pressure Pe, which is a conversion value of the evaporation temperature Te, and the outlet temperature Teo of the indoor heat exchangers 42, 52.

(2-2-2-8) Step S128: Low pressure gas pipe section H
Further, the control unit 8 calculates the refrigerant amount Mog2 in the low pressure gas pipe portion H based on the following equation 12 (S128).
[Equation 12]
Mog2 = Vog2 × ρs

  That is, the refrigerant amount Mog2 is expressed as a functional expression in which the volume Vog2 of the low pressure gas pipe portion H in the outdoor unit 2 is multiplied by the density ss of the refrigerant in the low pressure gas pipe portion H. The volume Vog2 of the low-pressure gas pipe section H is a known value before shipment to the installation site, and is stored in advance in the memory of the control unit 8.

(2-2-2-9) Step S129: Bypass Circuit I
Further, the control unit 8 calculates the refrigerant amount Mob in the bypass circuit unit I based on the following equation 13 (S129).
[Equation 13]
Mob = kob1 × ρco + kob2 × ρs + kob3 × Pe + kob4

  That is, the refrigerant amount Mob is expressed as a function of the density ρco of the refrigerant at the outlet of the outdoor heat exchanger 23, the density ρs of the refrigerant at the outlet on the bypass circuit side of the subcooler 25, and the evaporation pressure Pe. The parameters kob1 to kob3 are obtained by regression analysis of the results of the test and the detailed simulation, and are stored in advance in the memory of the control unit 8.

The volume Mob of the bypass circuit unit I may have a smaller amount of refrigerant than other portions, and may be calculated by a simpler relational expression. For example, the volume Mob of the bypass circuit unit I may be calculated by the following equation 14. In this case, the refrigerant amount Mob is expressed as a functional expression in which the volume Vob of the bypass circuit I is multiplied by the saturation liquid density ρe and the correction coefficient kob in the bypass circuit side of the subcooler 25. The volume Vob of the bypass circuit unit I is a known value before the outdoor unit 2 is installed at the installation location, and is stored in advance in the memory of the control unit 8. Further, the saturated liquid density ee in the portion on the bypass circuit side of the subcooler 25 is obtained by converting the suction pressure Ps or the evaporation temperature Te.
[Equation 14]
Mob = Vob × ρe × kob5

(2-2-2-10) Step S12A
Then, the control unit 8 calculates the amount of refrigerant charged in the entire refrigerant circuit 10 from the amount of refrigerant in each portion calculated in the above-described steps S121 to S129 (S12A).

  In the present embodiment, although one outdoor unit 2 is provided, when a plurality of outdoor units are connected, the refrigerant amounts Mog1, Mc, Mol1, Mol2, Mog2 and Mob related to the outdoor units are associated with a plurality of outdoors. A relational expression of the amount of refrigerant in each portion is set corresponding to each unit, and the total amount of refrigerant in the outdoor unit is calculated by adding the amounts of refrigerant in each portion of the plurality of outdoor units.

  The estimation of the amount of refrigerant according to step S12 described above is repeated until the process of the next step S13 is completed.

(2-2-3) Step S13: Determination of Appropriateness of Amount of Refrigerant As described above, when additional charging of the refrigerant into the refrigerant circuit 10 is started, the amount of refrigerant in the refrigerant circuit 10 gradually increases. At this time, the refrigerant amount M of the entire refrigerant circuit 10 is calculated from the state amount of the refrigerant flowing in the refrigerant circuit 10 or the operating state amount of the component. Then, additional charging of the refrigerant is performed until the calculated refrigerant amount M reaches the charging target value Ms.

  In other words, in the automatic refrigerant charging operation, it is determined whether the amount of refrigerant additionally charged in the refrigerant circuit 10 is appropriate or not by determining whether the value of the amount M of refrigerant in the entire refrigerant circuit 10 has reached the filling target value Ms. Do.

  In addition, in the above-mentioned refrigerant | coolant amount determination driving | operation, the refrigerant | coolant amount Mc in the outdoor heat exchanger 23 increases as the additional charge of the refrigerant | coolant in the refrigerant circuit 10 progresses, The refrigerant | coolant amount in another part becomes substantially constant. Therefore, the filling target value Ms is set as a value corresponding to only the refrigerant amount Mo of the outdoor unit 2 instead of the outdoor unit 2 and the indoor units 4 and 5, or corresponds to the refrigerant amount Mc of the outdoor heat exchanger 23. Alternatively, the refrigerant may be additionally charged until the target value Ms is reached, by setting it as a value to be set.

  Further, the refrigerant amount M of the entire refrigerant circuit 10 in the state where the filling target value Ms is reached and the additional charging of the refrigerant is completed determines the presence or absence of the leakage from the refrigerant circuit 10 in the "refrigerant leakage detection operation" described later. The reference refrigerant amount Mi of the entire refrigerant circuit 10 serving as a reference is used. The reference refrigerant amount Mi is stored in the memory of the control unit 8 as one of the operating state amounts.

(2-3) Refrigerant Leakage Detection Operation Mode FIG. 7 is a flowchart for explaining the refrigerant leak detection operation mode.

  The refrigerant leak detection operation is performed when inspecting whether the refrigerant leaks from the refrigerant circuit 10 to the outside due to an unforeseen cause.

  Specifically, when a normal operation such as a cooling operation or a heating operation has elapsed for a predetermined time (for example, every half year to one year, etc.), the normal operation mode is switched to the refrigerant leakage detection operation mode automatically or manually. In response to this, control unit 8 executes the processing of steps S21 to S24 shown in FIG. The process of each step will be described in detail below. In addition, refrigerant | coolant leak detection driving | operation is regularly performed at the time slot | zone etc. which do not need to air-condition on a holiday, midnight, etc.

(2-3-1) Step S21: Refrigerant Amount Estimation Operation When the start instruction of the refrigerant leakage detection operation is issued, the control portion 8 executes the above-described refrigerant amount estimation operation. That is, the control unit 8 executes the indoor unit 100% operation, the refrigerant circulation amount control, the condensation pressure control, the liquid pipe temperature control, and the superheat degree control. Here, the circulation amount target value Wcs in the refrigerant circulation amount control, the liquid pipe temperature target value Tlps in the liquid pipe temperature control, and the superheat degree target value SHrs in the superheat degree control are, in principle, the targets in step S11 of the refrigerant amount estimation operation. The same value as the value is used.

  The refrigerant amount estimation operation is performed each time the refrigerant leakage detection operation is performed, but the refrigerant circulation amount control is performed even when the refrigerant leakage occurs or the like, so the refrigerant circulation amount Wc is the same circulation amount The target value Wcs is kept constant. Further, even when the temperature Tco of the refrigerant at the outlet of the outdoor heat exchanger 23 fluctuates, the liquid pipe temperature control is performed, so the temperature Tlp of the refrigerant in the liquid refrigerant communication pipe 6 is the same as the liquid pipe temperature target value Tlps. Be kept constant.

(2-3-2) Step S22: Calculation of Refrigerant Amount Next, the controller 8 functioning as a refrigerant amount estimation unit that estimates the refrigerant amount while performing the above-described refrigerant amount estimation operation performs the refrigerant in the refrigerant leakage detection operation The refrigerant amount M of the entire refrigerant circuit 10 is calculated from the state amount of the refrigerant flowing through the circuit 10 or the operating state amount of the component. Here, the amount of refrigerant M in the entire refrigerant circuit 10 is calculated in the same manner as in steps S12 and S13 described above.

  The temperature Tlp of the refrigerant in the liquid refrigerant communication pipe 6 is kept constant at the liquid pipe temperature target value Tlps by the liquid pipe temperature control. Therefore, even when the temperature Tco of the refrigerant at the outlet of the outdoor heat exchanger 23 fluctuates, the refrigerant amount Mlp in the liquid refrigerant communication pipe B3 is kept constant regardless of the difference in the operating condition of the refrigerant leakage detection operation.

(2-3-3) Steps S23, S24: Determination of Appropriateness of Refrigerant Amount, Warning Display When the refrigerant leaks from the refrigerant circuit 10 to the outside, the amount of refrigerant in the refrigerant circuit 10 decreases. When the amount of refrigerant in the refrigerant circuit 10 decreases, the degree of subcooling SCo at the outlet of the outdoor heat exchanger 23 decreases. In addition, the amount of refrigerant Mc in the outdoor heat exchanger 23 decreases, and the amount of refrigerant in the other portions is kept substantially constant. Therefore, when the refrigerant leakage M from the refrigerant circuit 10 occurs, the refrigerant amount M of the entire refrigerant circuit 10 calculated in step S22 described above is calculated from the reference refrigerant amount Mi detected in the refrigerant automatic charging operation in the trial operation mode. Also becomes smaller. On the other hand, when the refrigerant leakage from the refrigerant circuit 10 does not occur, the value is substantially the same as the reference refrigerant amount Mi.

  Therefore, the presence or absence of the refrigerant leakage is determined by comparing the refrigerant amount M estimated by calculation with the reference refrigerant amount Mi. When it is determined that the refrigerant leakage from the refrigerant circuit 10 does not occur, the control unit 8 ends the refrigerant leakage detection operation (step S23-Yes).

  On the other hand, if it is determined in step S23 that the refrigerant leaks from the refrigerant circuit 10, the warning display unit 9 displays a warning notifying that the refrigerant leak has been detected, and then the refrigerant leak detection driving operation is performed. End (steps S23-No, S24).

  Thus, in the air conditioning apparatus 1 according to the present embodiment, the control unit 8 determines the appropriateness of the amount of refrigerant filled in the refrigerant circuit 10.

(3) Characteristics (3-1)
As described above, the air conditioner 1 according to the present embodiment includes the compressor 21, the outdoor heat exchanger 23, the indoor expansion valve 41, the indoor expansion valve 51, the outdoor expansion valve 38 (expansion mechanism), and the indoor It has the refrigerant circuit 10 comprised by connecting each component containing the heat exchangers 42 and 52. As shown in FIG. Here, the compressor 21 can change the operating capacity by changing the rotational speed.

  In the air conditioner 1 according to the present embodiment, the high temperature side liquid pipe portion B1 (first communication) in which the liquid refrigerant flows from the outdoor heat exchanger 23 toward the indoor heat exchangers 42, 52 during the refrigerant amount estimation operation Piping), a low pressure gas pipe section H (second connecting pipe) through which the gas refrigerant flows from the indoor heat exchangers 42 and 52 to the outdoor heat exchanger 23 during refrigerant quantity estimation operation, and the outdoor heat exchanger 23 And a bypass refrigerant circuit 61 (branch pipe) which is branched from the high temperature side liquid pipe portion B1 at the downstream portion and connected to the low pressure gas pipe portion H.

  The air conditioner 1 according to the present embodiment also includes the control unit 8. The control unit 8 controls the respective constituent devices to cause the indoor heat exchangers 42 and 52 to function as an evaporator, and executes the refrigerant amount estimating operation with the degree of superheat SHr higher than that in the normal operation. More specifically, at the time of refrigerant quantity estimation operation, the control unit 8 causes the indoor heat exchangers 42 and 52 to function as an evaporator, reduces the rotational speed of the compressor 21 regardless of the indoor load, and reduces the compressor speed. Each component is controlled so that the degree of superheat of the suctioned steam at 21 is stabilized for a predetermined time in a state higher than that in the normal operation. Here, in order to improve the estimation accuracy of the amount of refrigerant, the control unit 8 controls each component device such that a state in which the degree of superheat is higher than that in the normal operation continues for 5 minutes or more.

  Further, the control unit 8 also functions as a refrigerant amount estimation unit for estimating the refrigerant amount, and uses the state amount of the refrigerant flowing through the refrigerant circuit 10 in the refrigerant amount estimation operation or the operation state amount of each component device. The amount of refrigerant M in the inside is estimated.

  In such an air conditioning apparatus 1, it is possible to realize a refrigerant amount estimation method capable of estimating the refrigerant amount M in the refrigerant circuit 10 with high accuracy. Hereinafter, features of the refrigerant amount estimating method according to the present embodiment will be described in detail.

(3-2)
As described above, in the refrigerant amount estimation method according to the present embodiment, the control step (see step S11) and the estimation step (see step S12) are performed. In the control step, the respective constituent devices are controlled to cause the indoor heat exchangers 42, 52 to function as an evaporator, and to execute a refrigerant amount estimation operation that achieves a superheat degree SHr higher than that in normal operation (see step S116). . In the estimation step, the refrigerant amount M in the refrigerant circuit 10 is estimated using the state amount of the refrigerant flowing through the refrigerant circuit 10 in the refrigerant amount estimation operation or the operation state amount of each component.

  Therefore, in the refrigerant quantity estimation method according to the present embodiment, the liquid phase refrigerant quantity can be reduced in the indoor heat exchangers 42 and 52, which are evaporators, by setting the degree of superheat SHr higher than that in the normal operation. it can. Therefore, the refrigerant can be distributed to components other than the indoor heat exchangers 42 and 52 by executing the method of estimating the amount of refrigerant according to the present embodiment. In addition, the amount of refrigerant can be estimated with high accuracy using the experimental regression equation for the refrigerant present in the outdoor heat exchanger 23 or the like rather than the refrigerant present in the indoor heat exchangers 42, 52. As a result, the refrigerant amount M of the entire refrigerant circuit 10 can be estimated with high accuracy.

  Supplementally, the indoor units 4 and 5 have many variations, and it may be difficult to estimate the amount of refrigerant using an experimental regression equation. In that case, the refrigerant amount Mr of the indoor unit portion F is calculated by performing simulation of the refrigeration cycle characteristic (performing calculation of simultaneous equations of equations 6 to 8) (see step S126). However, when simulating the refrigeration cycle characteristics, completely eliminate the error because the correction term C and the virtual average liquid ratio e in the above-mentioned void ratio (equation 9) and Smith's equation (equation 10) are experimental parameters. Is difficult. In the refrigerant amount estimation method according to the present embodiment, since the refrigerant amount estimation operation with the superheat degree SHr higher than that in the normal operation is performed, in the indoor heat exchangers 42 and 52 (evaporator) The amount of refrigerant can be reduced. As a result, the refrigerant is distributed to components other than the indoor heat exchangers 42, 52, whereby the amount of refrigerant Mr in the indoor heat exchangers 42, 52 (evaporator) relative to the amount of refrigerant M of the entire refrigerant circuit 10 is relative. The error of the refrigerant amount M of the entire refrigerant circuit 10 can be reduced. As a result, the refrigerant amount M in the refrigerant circuit 10 can be estimated with high accuracy.

  The term "normal operation" as used herein refers to an operating state in which the degree of superheat is 3 to 5 degrees, and the inverter rotational speed is varied according to the indoor heat load to provide a cooling capacity according to the load. For example, the normal operation is an operation in which the degree of superheat is about 3 to 5 degrees, and the evaporation temperature is 10 degrees or more when the indoor temperature is 20 degrees or more.

(3-3)
Moreover, the refrigerant | coolants amount estimation method which concerns on this embodiment makes superheat degree SHr within the range of 10 degrees or more and 20 degrees or less at the control step at the time of refrigerant | coolant amount estimation driving | operation. Further, the calculation of the amount of refrigerant is performed at the timing when the degree of superheat SHr becomes stable at a value within the range of 10 degrees to 20 degrees. Thus, the refrigerant amount M in the refrigerant circuit 10 can be estimated with high accuracy while maintaining the reliability. Supplementally, by setting the degree of superheat SHr to 10 degrees or more, the dry region in the indoor heat exchangers 42 and 52 functioning as the evaporator can be increased, and the refrigerant amount Mr of the indoor unit portion F can be decreased. As a result, it is possible to reduce the calculation error when calculating the refrigerant amount M of the entire refrigerant circuit 10. On the other hand, if the degree of superheat SHr exceeds 20 degrees, the compressor discharge temperature may exceed the reliability temperature upper limit. Therefore, the reliability can be maintained by setting the degree of superheat SHr to 20 degrees or less.

  Here, when calculating the refrigerant amount M, the degree of superheat SHr is in the range of 10 degrees or more and 20 degrees or less, but it is not necessary to be limited to this, and if the degree of superheat SHr is 5 degrees or more Just do it. If the degree of superheat is 5 degrees or more, the dry region of the indoor heat exchanger can be increased as compared with the normal operation, and the refrigerant amount M can be calculated with high accuracy.

(3-4)
Moreover, the refrigerant | coolants amount estimation method which concerns on this embodiment operate | moves the air conditioning apparatus 1 at evaporation temperature Te lower than normal driving | operating at the time of refrigerant | coolant amount estimation driving | operation. Specifically, the evaporation temperature Te is set in the range of 0 degrees Celsius or more and 10 degrees Celsius or less. Further, the calculation of the amount of refrigerant is performed at the timing when the evaporation temperature Te becomes stable in the range of 0 degrees Celsius or more and 10 degrees Celsius or less. As a result, the amount of refrigerant in the liquid phase can be reduced in the indoor heat exchangers 42, 52. As a result, it is possible to reduce the calculation error when calculating the refrigerant amount of the entire refrigerant circuit 10. By setting the evaporation temperature Te to 0 ° C. or higher, frost can be prevented from being generated in the indoor heat exchangers 42 and 52 functioning as an evaporator. Further, by setting the evaporation temperature Te to 10 ° C. or less, the refrigerant amount estimation operation can be performed under substantially any indoor temperature condition.

  In addition, according to examination of the present inventors, as shown in FIG. 8, it is clear that the amount of refrigerant in the evaporator section C can be reduced by lowering the evaporation temperature Te. Here, in FIG. 8, line L1 indicates the amount of refrigerant in the indoor heat exchanger when the evaporation temperature is 10 ° C., and line L2 indicates the amount in the indoor heat exchanger when the evaporation temperature is 5 ° C. The amount of refrigerant is shown, line L3 shows the amount of refrigerant in the liquid phase in the indoor exchanger when the evaporation temperature is 10 ° C, and line L4 is the inside of the indoor exchanger when the evaporation temperature is 5 ° C Indicates the amount of liquid phase refrigerant.

(3-5)
Moreover, the refrigerant quantity estimation method according to the present embodiment changes the rotation speed of the compressor 21 so that the refrigerant circulation quantity Wc becomes constant in the refrigerant quantity estimation operation (see step S113).

  As described above, in the refrigerant amount estimation operation, the rotational speed of the compressor 21 is changed so that the refrigerant circulation amount Wc becomes constant, so the degree of supercooling SCo of the outlet of the outdoor heat exchanger 23 functioning as a condenser The linearity of the correlation between the amount of liquid refrigerant accumulated in the outdoor heat exchanger 23 and the inside becomes excellent. Further, the calculation of the amount of refrigerant is performed at the timing when the amount of circulation of the refrigerant in the refrigerant circuit 10 becomes stable at a value of 40% or less than in the rated operation. Thereby, the amount of refrigerant of outdoor heat exchanger 23 can be computed using a highly accurate experimental regression. As a result, the amount of refrigerant M in the refrigerant circuit 10 can be estimated with higher accuracy.

  Supplementally, the condenser is controlled by controlling the constituent devices so that the refrigerant circulation amount Wc of the refrigerant circulating in the refrigerant circuit 10 becomes constant (more specifically, the circulation amount target value Wcs). The distribution state of the gas refrigerant and the liquid refrigerant inside the outdoor heat exchanger 23 that functions can be stabilized. Therefore, from the fluctuation of the degree of supercooling SCo at the outlet of the outdoor heat exchanger 23, it is possible to exclude the non-linear component generated due to the change of the refrigerant circulation amount Wc. Thereby, the fluctuation of the degree of subcooling SCo at the outlet of the outdoor heat exchanger 23 is mainly caused by the change of the amount of refrigerant inside the outdoor heat exchanger 23. Therefore, the air conditioner 1 does not use a method with a large operation load such as simulation of refrigeration cycle characteristics (here, as represented by a relational expression for calculating the refrigerant amount Mc of the condenser section A High accuracy of the suitability of the amount of refrigerant in the refrigerant circuit 10 (here, the amount of refrigerant M in the entire refrigerant circuit 10) by using a relational expression consisting of primary terms for calculating the amount of refrigerant in each part of the refrigerant circuit 10 Can be determined.

(3-6)
Further, in the refrigerant amount estimation method according to the present embodiment, the refrigerant circulation amount Wc is calculated from the state amount of the refrigerant flowing through the refrigerant circuit 10 or the operation state amount of the component device. Specifically, the evaporation temperature Te, the condensation temperature Tc, the suction temperature Ts which is the refrigerant temperature at the suction side of the compressor 21, the suction pressure Ps which is the refrigerant pressure at the suction side of the compressor 21, the discharge pressure at the discharge side of the compressor 21 Discharge temperature Td which is the refrigerant temperature, discharge pressure Pd which is the refrigerant pressure on the discharge side of the compressor 21, compressor discharge superheat degree SHm which is the degree of superheat of the refrigerant on the inlet side of the outdoor heat exchanger 23 as a condenser, The refrigerant circulation amount Wc is calculated using at least one of the subcooling degree SCo, which is the degree of subcooling of the refrigerant at the outlet side of the outdoor heat exchanger 23 as a condenser. Thereby, in the air conditioning apparatus 1, a flow meter for detecting the refrigerant circulation amount Wc becomes unnecessary.

(3-7)
Further, in the method of estimating the amount of refrigerant according to the present embodiment, in the control step, each component is controlled to make the refrigerant circulation amount Wc of the refrigerant in the refrigerant circuit 10 lower than that in rated operation. Perform estimated driving. Specifically, the control unit 8 executes the refrigerant amount estimation operation such that the refrigerant circulation amount Wc is 40% or less than that in the rated operation (see step S113).

  As described above, the refrigerant flow in each heat exchanger is stabilized by executing the refrigerant amount estimation operation such that the refrigerant circulation amount Wc of the refrigerant in the refrigerant circuit 10 is lower than that in the rated operation. Can. Thereby, the reproducibility and repeatability can be enhanced, and the refrigerant amount M in the refrigerant circuit 10 can be estimated with high accuracy.

  When the refrigerant circulation amount Wc is too low, the high pressure refrigerant may be insufficient, which may result in the case where the heating and cooling capacity is not sufficiently exhibited. Therefore, when performing the refrigerant amount estimation operation, the minimum value of the refrigerant circulation amount Wc is set to such an extent that the air conditioning capacity can be sufficiently exhibited.

(3-8)
Further, in the refrigerant amount estimation method according to the present embodiment, in the control step, the refrigerant in the bypass refrigerant circuit 61 is adjusted in flow rate and reduced in pressure by the bypass expansion valve 62 (flow valve), and the high temperature side liquid pipe portion B1 (first Heat exchange between the refrigerant in the main refrigerant circuit not flowing into the bypass refrigerant circuit 61 (branch piping) from the connection pipe) and the refrigerant flowing into the bypass refrigerant circuit 61 via the subcooler 25 (heat exchanger), The refrigerant flowing into the bypass refrigerant circuit 61 is merged with the refrigerant in the low pressure gas pipe portion H (second connection pipe) (see step S115). At this time, liquid pipe temperature control is realized by adjusting the heat exchange amount in the subcooler 25. Thereby, the liquid refrigerant in the liquid refrigerant communication pipe 6 can be brought into the subcooling state, and the evaporation temperature Te lower than in the normal operation can be easily realized. As a result, the refrigerant amount M can be detected with high accuracy.

  Supplementally, since the subcooler 25 functions as a temperature control mechanism, it becomes possible to adjust the temperature of the refrigerant sent from the outdoor heat exchanger 23 as a condenser to the indoor expansion valves 41, 51 as an expansion mechanism. . As a result, during the refrigerant amount estimation operation, the temperature Tlp of the refrigerant sent from the subcooler 25 to the indoor expansion valves 41 and 51 as the expansion mechanism can be made constant. Therefore, the density lplp of the refrigerant in the refrigerant pipe from the subcooler 25 to the indoor expansion valves 41, 51 can be prevented from changing. In addition, even when the refrigerant temperature Tco at the outlet of the outdoor heat exchanger 23 is different every time the refrigerant amount estimation operation is performed, the influence of the difference in the temperature of the refrigerant is determined by the outlet of the outdoor heat exchanger 23 Can be stored only in the refrigerant pipe leading to the subcooler 25. As a result, when estimating the amount of refrigerant, it is possible to reduce an error due to the difference in temperature Tco of the refrigerant at the outlet of the outdoor heat exchanger 23 (that is, the difference in density of the refrigerant).

  In particular, as in the present embodiment, when the outdoor unit 2 as a heat source unit and the indoor units 4 and 5 as a utilization unit are connected via the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 7, The length, the pipe diameter, etc. of the refrigerant communication pipes 6, 7 connecting the outdoor unit 2 and the indoor units 4, 5 differ depending on the conditions such as the installation place. Therefore, when the volumes of the refrigerant communication pipes 6, 7 increase, the difference in the temperature Tco of the refrigerant at the outlet of the outdoor heat exchanger 23 is the refrigerant reaching the indoor expansion valves 41, 51 from the outlet of the outdoor heat exchanger 23. Since the temperature of the refrigerant in the liquid refrigerant communication pipe 6 constituting the majority of the pipe is different, the estimation error of the amount of refrigerant becomes large.

  On the other hand, as described above, the supercooler 25 is provided, and the capacity control of the supercooler 25 is performed so that the temperature Tlp of the refrigerant in the liquid refrigerant communication pipe 6 becomes constant during the refrigerant quantity determination operation. This makes it possible to prevent the density 冷媒 lp of the refrigerant in the refrigerant pipe extending from the subcooler 25 to the indoor expansion valves 41 and 51 from changing. Therefore, when estimating the amount of refrigerant, it is possible to reduce the error due to the difference in the temperature Tco of the refrigerant at the outlet of the outdoor heat exchanger 23 (that is, the difference in the density of the refrigerant).

  As a result, for example, in the refrigerant automatic charging operation for charging the refrigerant in the refrigerant circuit 10, it can be determined with high accuracy whether the refrigerant amount M of the entire refrigerant circuit 10 has reached the reference refrigerant amount Mi. . Further, in the refrigerant leakage detection operation for determining the presence or absence of the refrigerant leakage from the refrigerant circuit 10, the presence or absence of the refrigerant leakage from the refrigerant circuit 10 can be determined with high accuracy.

(3-9)
Moreover, in the refrigerant | coolants amount estimation method of this embodiment, the refrigerant circuit 10 is divided | segmented into several parts, and the relational expression of the refrigerant | coolant amount of each part and a driving | running state amount is set. Therefore, the calculation load can be suppressed by minimizing the portion where the simulation of the refrigeration cycle characteristics (the simultaneous equations of Equations 6 to 8) is performed. In addition, it is possible to selectively capture an operating condition amount that is important in calculating the amount of refrigerant in each portion as a variable of the relational expression. As a result, the calculation accuracy of the amount of refrigerant in each portion is improved, and the suitability of the amount of refrigerant M in the refrigerant circuit 10 can be determined with high accuracy.

(3-10)
Further, in the refrigerant amount estimation method according to the present embodiment, the states of the indoor heat exchangers 42 and 52, which are evaporators, can be reproduced in the same manner under any of the conditions of the outside air temperature and the room temperature by the above-described control. Also, it has the effect that errors do not easily occur when the test operation is performed at different outside temperatures and room temperatures.

(3-11)
Moreover, in the refrigerant | coolant amount estimation method which concerns on this embodiment, a refrigerant | coolant amount can be estimated, without attaching a liquid level sensor to accumulator 24 grade | etc.,. As a result, it is possible to estimate the refrigerant amount with high accuracy without causing cost increase.

(3-12)
In addition, the air conditioning apparatus 1 mentioned above has some indoor units 4 and 5 which have indoor heat exchangers 42 and 52 separately. Then, the control unit 8 controls each component device so that the degree of superheat of all the indoor units 4 and 5 in operation is stabilized in a state higher than the normal operation. Such a configuration makes it possible to estimate the amount of refrigerant in the refrigerant circuit with high accuracy in the air conditioning apparatus 1 having the plurality of indoor units 4 and 5.

  Supplementally, in the air conditioner 1 described above, air conditioning of different spaces (for example, rooms) is performed by the indoor units 4 and 5. Here, since the temperature in each space is different, there is a possibility that even in normal operation, when a certain indoor unit is used, the degree of superheat may increase. However, when all indoor units are used, it does not generally occur that the operation has a large degree of superheat. Under such premise, in the air conditioner 1 according to the present embodiment, the control unit 8 stabilizes the degree of superheat of all the indoor units in operation higher than in the normal operation, unlike the normal operation. To control each component.

(4) Modifications (4-1) Modification A
The air conditioner 1 according to the present embodiment includes the flow paths B1, B2, and B3 (connection pipes) in which the liquid refrigerant flows from the outdoor heat exchanger 23 toward the indoor heat exchangers 42 and 52 during the refrigerant amount estimation operation. A control unit 8 (temperature control device) that controls the temperature of the flow path, an outdoor fan 28 that changes the temperature of the outdoor heat exchanger 23, and an indoor fan 43 that changes the temperature of the indoor heat exchangers 42 and 52, And 53. And in this air conditioning apparatus 1, the evaporation temperature Te and the condensation temperature Tc in the refrigerant circuit 10, the degree of supercooling SCo corresponding to the difference between the temperature of the liquid refrigerant in the connection pipe and the condensation temperature, and the degree of superheat SHr in the refrigerant amount estimation operation. The refrigerant circulation amount Wc is set to a target value according to the indoor temperature Tr and the outdoor temperature Ta.

  In the modified example A, when all of the evaporation temperature Te, the condensation temperature Tc, the degree of supercooling SCo, the degree of superheat SHr, and the refrigerant circulation amount Wc reach the predetermined range from the target value in the control step. Control is performed so as to fix the values of the rotation speed of the compressor 21, the control output of the temperature control device, the opening degree of the expansion mechanism, the rotation speed of the outdoor fan 28, and the rotation speed of the indoor fans 43 and 53.

  Such control may stabilize the refrigerant flow more than PID control. As a result, the refrigerant amount M in the refrigerant circuit 10 can be estimated with high accuracy.

(4-2) Modification B
Although the air conditioning apparatus 1 has the bypass circuit unit I in the above description, the air conditioning apparatus 1 according to the present embodiment is not limited to such a configuration. Specifically, as shown in FIG. 9, the air conditioning apparatus 1 according to the present embodiment may not have the bypass circuit unit I. With such a configuration, the air conditioner 1 with reduced cost can be realized.

  In addition, in the case of the structure which does not have the bypass circuit unit I, the overcooling is controlled as a matter of course.

(4-3) Modification C
Although the said description demonstrated using the air conditioning apparatus 1 which can be switched between cooling and heating, the air conditioning apparatus 1 which concerns on this embodiment is not limited to such a structure. For example, an air conditioner dedicated to cooling may be used. Moreover, although the said description demonstrated using the air conditioning apparatus 1 provided with one outdoor unit, the air conditioning apparatus 1 which concerns on this embodiment is not limited to such a structure. For example, the air conditioner may be provided with a plurality of outdoor units.

(4-4) Modification D
In the above description, the air conditioning apparatus 1 includes the plurality of indoor units 4 and 5 having the indoor heat exchangers 42 and 52 individually, but the refrigerant quantity estimation method according to the present embodiment is other than the air conditioning It can also be used for the device 1.

  For example, as shown in FIG. 10, the same refrigerant amount estimation method can be applied to the air conditioner 1D in which one indoor unit 4 corresponds to one outdoor unit 2. In the configuration shown in FIG. 10, the outdoor unit 2 includes the outdoor heat exchanger 23, and the indoor unit 4 includes the indoor heat exchanger 42. The other configuration is the same as that shown in FIG. 9, but the specific configuration of each device is adopted optimally according to the usage form.

  In addition, in this air conditioning apparatus 1D, the control unit 8 preferably controls each component device so that the degree of superheat is 8 degrees or more.

(4-5) Modification E
Although the control part 8 of the air conditioning apparatus 1 performed calculation of the refrigerant quantity M in the said description, the air conditioning apparatus 1 which concerns on this embodiment is not restricted to such a structure. For example, when the air conditioning apparatus 1 has a function of communicating with the management apparatus on the network, the control unit 8 of the air conditioning apparatus 1 does not execute the calculation of the refrigerant quantity M, and the management apparatus performs the refrigerant quantity It may be in the form of executing the operation of M. In addition, in the case of such a form, the information required for calculation is transmitted to the management apparatus from the air conditioning apparatus 1 as needed.

<Supplementary Note>
The present invention is not limited to the above embodiments. In the implementation stage, the present invention can be embodied by modifying the constituent elements without departing from the scope of the invention. In addition, the present invention can form various inventions by appropriate combinations of a plurality of constituent elements disclosed in each of the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, the components may be combined as appropriate in different embodiments.

1 Air conditioner 8 control unit (control unit) (estimation unit) (temperature control device)
DESCRIPTION OF SYMBOLS 10 Refrigerant circuit 21 Compressor 23 Outdoor heat exchanger 25 Supercooler (heat exchanger)
28 Outdoor fan 38 Outdoor expansion valve (expansion mechanism)
41 Indoor expansion valve (expansion mechanism)
42 indoor heat exchanger 43 indoor fan 51 indoor expansion valve (expansion mechanism)
52 indoor heat exchanger 53 indoor fan 61 bypass refrigerant circuit (branch piping)
62 Bypass expansion valve (flow valve)
B1 High temperature side liquid pipe (1st connection piping)
B2 Low temperature side liquid pipe (communication piping)
B3 Liquid refrigerant communication piping (communication piping)
H low pressure gas pipe section (second connecting piping)

Patent No. 4705878 gazette

In the refrigerant quantity estimation method according to the third aspect , the degree of superheat is in the range of 10 degrees or more and 20 degrees or less at the time of refrigerant quantity estimation operation. Thus, it is possible to estimate the amount of refrigerant in the refrigerant circuit with high accuracy while maintaining the reliability. Supplementally, by setting the degree of superheat to 10 degrees or more, the dry area in the indoor heat exchanger functioning as an evaporator can be increased, and the amount of refrigerant can be reduced. As a result, it is possible to reduce the calculation error when calculating the amount of refrigerant in the entire refrigerant circuit. On the other hand, if the degree of superheat exceeds 20 degrees, the compressor discharge temperature may exceed the reliability temperature upper limit. Therefore, the reliability can be maintained by setting the degree of superheat to 20 degrees or less.

Claims (14)

Each component is connected by including a compressor (21), an outdoor heat exchanger (23), an expansion mechanism (41, 51, 38), and at least one indoor heat exchanger (42, 52) An air conditioner (1) having a refrigerant circuit (10)
The indoor heat exchanger functions as an evaporator, and the rotational speed of the compressor is reduced regardless of the indoor load, and the compressor is stabilized for a predetermined time in a state where the degree of superheat of the suctioned vapor is higher than that in normal operation. Control unit configured to control each of the component devices to
Air conditioner. It has a plurality of indoor units (4, 5) individually having the indoor heat exchangers,
The control unit controls the respective constituent devices so that the degree of superheat of all indoor units in operation is stabilized in a state higher than normal operation.
The air conditioner according to claim 1. The control unit controls the respective constituent devices so that the degree of superheat is 5 degrees or more.
An air conditioner according to claim 1 or 2. The outdoor unit having the outdoor heat exchanger and the indoor unit having the indoor heat exchanger are provided, and one indoor unit corresponds to one outdoor unit,
The control unit controls the respective constituent devices so that the degree of superheat is 8 degrees or more.
The air conditioner according to claim 1. The control unit controls each component device such that a state in which the degree of superheat is higher than that in normal operation lasts for 5 minutes or more.
The air conditioner according to any one of claims 1 to 4. The control unit calculates the amount of refrigerant in the refrigerant circuit using the amount of state of refrigerant flowing through the refrigerant circuit or the amount of operating state of each component.
The air conditioner according to any one of claims 1 to 5. The controller sets the degree of superheat within a range of 10 degrees to 20 degrees when calculating the amount of refrigerant in the refrigerant circuit.
The air conditioner according to claim 6. Each component is connected by including a compressor (21), an outdoor heat exchanger (23), an expansion mechanism (41, 51, 38), and at least one indoor heat exchanger (42, 52) A control method for calculating the amount of refrigerant in an air conditioner (1) having a refrigerant circuit (10),
The indoor heat exchanger functions as an evaporator, the rotational speed of the compressor is reduced regardless of the indoor load, and the heating degree of suctioned vapor in the compressor is stabilized for a predetermined time in a state higher than that in normal operation Control method to control each of the component devices to do so. The air conditioner includes a plurality of indoor units individually having the indoor heat exchangers,
Control the components so that the degree of superheat of all indoor units in operation is stabilized at a higher level than in normal operation,
The control method according to claim 8. Control each of the components so that the degree of superheat is 5 degrees or more,
The control method according to claim 8 or 9. The air conditioner has an outdoor unit having the outdoor heat exchanger and an indoor unit having the indoor heat exchanger, and one indoor unit corresponds to one outdoor unit. Yes,
Control each of the components so that the degree of superheat is 8 degrees or more,
The control method according to claim 8. Control each component such that the state of superheat higher than in normal operation lasts for 5 minutes or more,
The control method according to any one of claims 8 to 11. After executing the control according to any one of claims 8 to 12, the amount of refrigerant in the refrigerant circuit is determined using the amount of state of the refrigerant flowing through the refrigerant circuit or the amount of operating state of each component. calculate,
Refrigerant amount estimation method. When calculating the amount of refrigerant in the refrigerant circuit, the degree of superheat is in the range of 10 degrees to 20 degrees.
The refrigerant | coolant amount estimation method of Claim 13.

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